stackoverflow answer - Page 653

What version-control system is most trivial to set up and use for toy projects?

- by Norman Ramsey

I teach the third required intro course in a CS department. One of my homework assignments asks students to speed up code they have written for a previous assignment. Factor-of-ten speedups are routine; factors of 100 or 1000 are not unheard of. (For a factor of 1000 speedup you have to have made rookie mistakes with malloc().) Programs are improved by a sequence is small changes. I ask students to record and describe each change and the resulting improvement. While you're improving a program it is also possible to break it. Wouldn't it be nice to back out? You can see where I'm going with this: my students would benefit enormously from version control. But there are some caveats: Our computing environment is locked down. Anything that depends on a central repository is suspect. Our students are incredibly overloaded. Not just classes but jobs, sports, music, you name it. For them to use a new tool it has to be incredibly easy and have obvious benefits. Our students do most work in pairs. Getting bits back and forth between accounts is problematic. Could this problem also be solved by distributed version control? Complexity is the enemy. I know setting up a CVS repository is too baffling---I myself still have trouble because I only do it once a year. I'm told SVN is even harder. Here are my comments on existing systems: I think central version control (CVS or SVN) is ruled out because our students don't have the administrative privileges needed to make a repository that they can share with one other student. (We are stuck with Unix file permissions.) Also, setup on CVS or SVN is too hard. darcs is way easy to set up, but it's not obvious how you share things. darcs send (to send patches by email) seems promising but it's not clear how to set it up. The introductory documentation for git is not for beginners. Like CVS setup, it's something I myself have trouble with. I'm soliciting suggestions for what source-control to use with beginning students. I suspect we can find resources to put a thin veneer over an existing system and to simplify existing documentation. We probably don't have resources to write new documentation. So, what's really easy to setup, commit, revert, and share changes with a partner but does not have to be easy to merge or to work at scale? A key constraint is that programming pairs have to be able to share work with each other and only each other, and pairs change every week. Our infrastructure is Linux, Solaris, and Windows with a netapp filer. I doubt my IT staff wants to create a Unix group for each pair of students. Is there an easier solution I've overlooked? (Thanks for the accepted answer, which beats the others on account of its excellent reference to Git Magic as well as the helpful comments.)

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Socket php server not showing messages sent from android client

- by Mj1992

Hi I am a newbie in these kind of stuff but here's what i want to do. I am trying to implement a chat application in which users will send their queries from the website and as soon as the messages are sent by the website users.It will appear in the android mobile application of the site owner who will answer their queries .In short I wanna implement a live chat. Now right now I am just simply trying to send messages from android app to php server. But when I run my php script from dreamweaver in chrome the browser keeps on loading and doesn't shows any output when I send message from the client. Sometimes it happened that the php script showed some outputs which I have sent from the android(client).But i don't know when it works and when it does not. So I want to show those messages in the php script as soon as I send those messages from client and vice versa(did not implemented the vice versa for client but help will be appreciated). Here's what I've done till now. php script: <?php set_time_limit (0); $address = '127.0.0.1'; $port = 1234; $sock = socket_create(AF_INET, SOCK_STREAM, 0); socket_bind($sock, $address, $port) or die('Could not bind to address'); socket_listen($sock); $client = socket_accept($sock); $welcome = "Roll up, roll up, to the greatest show on earth!\n? "; socket_write($client, $welcome,strlen($welcome)) or die("Could not send connect string\n"); do{ $input=socket_read($client,1024,1) or die("Could not read input\n"); echo "User Says: \n\t\t\t".$input; if (trim($input) != "") { echo "Received input: $input\n"; if(trim($input)=="END") { socket_close($spawn); break; } } else{ $output = strrev($input) . "\n"; socket_write($spawn, $output . "? ", strlen (($output)+2)) or die("Could not write output\n"); echo "Sent output: " . trim($output) . "\n"; } } while(true); socket_close($sock); echo "Socket Terminated"; ?> Android Code: public class ServerClientActivity extends Activity { private Button bt; private TextView tv; private Socket socket; private String serverIpAddress = "127.0.0.1"; private static final int REDIRECTED_SERVERPORT = 1234; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); bt = (Button) findViewById(R.id.myButton); tv = (TextView) findViewById(R.id.myTextView); try { InetAddress serverAddr = InetAddress.getByName(serverIpAddress); socket = new Socket(serverAddr, REDIRECTED_SERVERPORT); } catch (UnknownHostException e1) { e1.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } bt.setOnClickListener(new OnClickListener() { public void onClick(View v) { try { EditText et = (EditText) findViewById(R.id.EditText01); String str = et.getText().toString(); PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true); out.println(str); Log.d("Client", "Client sent message"); } catch (UnknownHostException e) { tv.setText(e.getMessage()); e.printStackTrace(); } catch (IOException e) { tv.setText(e.getMessage()); e.printStackTrace(); } catch (Exception e) { tv.setText(e.getMessage()); e.printStackTrace(); } } }); } } I've just pasted the onclick button event code for Android.Edit text is the textbox where I am going to enter my text. The ip address and port are same as in php script.

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How do I process the largest match first in PHP?

- by animuson

Ok, so I tried searching around first but I didn't exactly know how to word this question or a search phrase. Let me explain. I have data that looks like this:   0,9 0,0 9,0 9,9 0,9   1,5 1,6 3,6 3,8 4,8   0,7 1,7   So it's basically a bunch of points. Here is the code I'm currently using to try and parse it so that it would create an array like so: Array ( 0 => Array ( 0 => "0,9", 1 => "0,0", 2 => "9,0", 3 => "9,9", 4 => "0,9" ), 1 => Array ( 0 => "1,5", 1 => "1,6", 2 => "3,6", 3 => "3,8", 4 => "4,8" ), 2 => Array ( 0 => "0,7", 1 => "1,7" ) ) However, it is returning an array that looks like this: Array ( 0 => "0,9", 1 => "0,0", 2 => "9,0" ) Viewing the larger array that I have on my screen, you see that it's setting the first instance of that variable when matching. So how do I get it to find the widest match first and then process the insides. Here is the function I am currently using: function explosion($text) { $number = preg_match_all("/()\n?(.*?)\n?()/s", $text, $matches, PREG_SET_ORDER); if ($number == 0) return $text; else unset($item); foreach ($matches as $item) if (empty($data[$item[2]])) $data[$item[2]] = $this->explosion($item[3]); return $data; } I'm sure it will be something stupid and simple that I've overlooked, but that just makes it an easy answer for you I suppose.

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Get item from spinner into url

- by ShadowCrowe

I searched for an answer but couldn't find it. The problem: Depending on the selected spinner-item the application should show a different image. At this moment I can't get it to work. The Url works like this: "my.site.com/images/" imc_met ".png" were imc_met is the filename. I can't get it to work. Btw the app isn't finished yet package example.myapplication; import java.io.IOException; import java.net.MalformedURLException; import java.net.URI; import java.net.URISyntaxException; import java.net.URL; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.ImageView; import android.widget.Spinner; public class itemsActivity extends Activity { private Spinner spinner1, spinner2; private Button btnSubmit; private Bitmap image; private ImageView imageView; private String imc_met, imc; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.items); addItemsOnSpinner2(); addListenerOnButton(); addListenerOnSpinnerItemSelection(); } // add items into spinner dynamically public void addItemsOnSpinner2() { spinner2 = (Spinner) findViewById(R.id.spinner2); List<String> list = new ArrayList<String>(); list.add("list 1"); list.add("list 2"); list.add("list 3"); ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, list); dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner2.setAdapter(dataAdapter); } public void addListenerOnSpinnerItemSelection() { spinner1 = (Spinner) findViewById(R.id.spinner1); spinner1.setOnItemSelectedListener(new CustomOnItemSelectedListener()); } // get the selected dropdown list value public void addListenerOnButton() { spinner1 = (Spinner) findViewById(R.id.spinner1); spinner2 = (Spinner) findViewById(R.id.spinner2); btnSubmit = (Button) findViewById(R.id.btnSubmit); spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { @Override public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) { if(spinner1.getSelectedItem()!=null){ imc_met = spinner1.getSelectedItem().toString(); } } @Override public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub } }); imageView = (ImageView)findViewById(R.id.ImageView01); btnSubmit.setOnClickListener(new OnClickListener() { public void onClick(View v) { URL url = null; try { url = new URL("my.site.com"); //here should the right link appear. } catch (MalformedURLException e) { e.printStackTrace(); } try { if (url != null) { image = BitmapFactory.decodeStream(url.openStream()); } } catch (IOException e) { e.printStackTrace(); } imageView.setImageBitmap(image); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }

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StoreGeneratedPattern T4 EntityFramework concern

- by LoganWolfer

Hi everyone, Here's the situation : I use SQL Server 2008 R2, SQL Replication, Visual Studio 2010, EntityFramework 4, C# 4. The course-of-action from our DBA is to use a rowguid column for SQL Replication to work with our setup. These columns need to have a StoreGeneratedPattern property set to Computed on every one of these columns. The problem : Every time the T4 template regenerate our EDMX (ADO.NET Entity Data Model) file (for example, when we update it from our database), I need to go manually in the EDMX XML file to add this property to every one of them. It has to go from this : <Property Name="rowguid" Type="uniqueidentifier" Nullable="false" /> To this : <Property Name="rowguid" Type="uniqueidentifier" Nullable="false" StoreGeneratedPattern="Computed"/> The solution : I'm trying to find a way to customize an ADO.NET EntityObject Generator T4 file to generate a StoreGeneratedPattern="Computed" to every rowguid that I have. I'm fairly new to T4, I only did customization to AddView and AddController T4 templates for ASP.NET MVC 2, like List.tt for example. I've looked through the EF T4 file, and I can't seem to find through this monster where I could do that (and how). My best guess is somewhere in this part of the file, line 544 to 618 of the original ADO.NET EntityObject Generator T4 file : //////// //////// Write PrimitiveType Properties. //////// private void WritePrimitiveTypeProperty(EdmProperty primitiveProperty, CodeGenerationTools code) { MetadataTools ef = new MetadataTools(this); #> /// <summary> /// <#=SummaryComment(primitiveProperty)#> /// </summary><#=LongDescriptionCommentElement(primitiveProperty, 1)#> [EdmScalarPropertyAttribute(EntityKeyProperty=<#=code.CreateLiteral(ef.IsKey(primitiveProperty))#>, IsNullable=<#=code.CreateLiteral(ef.IsNullable(primitiveProperty))#>)] [DataMemberAttribute()] <#=code.SpaceAfter(NewModifier(primitiveProperty))#><#=Accessibility.ForProperty(primitiveProperty)#> <#=code.Escape(primitiveProperty.TypeUsage)#> <#=code.Escape(primitiveProperty)#> { <#=code.SpaceAfter(Accessibility.ForGetter(primitiveProperty))#>get { <#+ if (ef.ClrType(primitiveProperty.TypeUsage) == typeof(byte[])) { #> return StructuralObject.GetValidValue(<#=code.FieldName(primitiveProperty)#>); <#+ } else { #> return <#=code.FieldName(primitiveProperty)#>; <#+ } #> } <#=code.SpaceAfter(Accessibility.ForSetter((primitiveProperty)))#>set { <#+ if (ef.IsKey(primitiveProperty)) { if (ef.ClrType(primitiveProperty.TypeUsage) == typeof(byte[])) { #> if (!StructuralObject.BinaryEquals(<#=code.FieldName(primitiveProperty)#>, value)) <#+ } else { #> if (<#=code.FieldName(primitiveProperty)#> != value) <#+ } #> { <#+ PushIndent(CodeRegion.GetIndent(1)); } #> <#=ChangingMethodName(primitiveProperty)#>(value); ReportPropertyChanging("<#=primitiveProperty.Name#>"); <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>); ReportPropertyChanged("<#=primitiveProperty.Name#>"); <#=ChangedMethodName(primitiveProperty)#>(); <#+ if (ef.IsKey(primitiveProperty)) { PopIndent(); #> } <#+ } #> } } private <#=code.Escape(primitiveProperty.TypeUsage)#> <#=code.FieldName(primitiveProperty)#><#=code.StringBefore(" = ", code.CreateLiteral(primitiveProperty.DefaultValue))#>; partial void <#=ChangingMethodName(primitiveProperty)#>(<#=code.Escape(primitiveProperty.TypeUsage)#> value); partial void <#=ChangedMethodName(primitiveProperty)#>(); <#+ } Any help would be appreciated. Thanks in advance. EDIT : Didn't find answer to this problem yet, if anyone have ideas to automate this, would really be appreciated.

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Update transaction in SQL Server 2008 R2 from ASP.Net not working

- by Amarus

Hello! Even though I've been a stalker here for ages, this is the first post I'm making. Hopefully, it won't end here and more optimistically future posts might actually be me trying to give a hand to someone else, I do owe this community that much and more. Now, what I'm trying to do is simple and most probably the reason behind it not working is my own stupidity. However, I'm stumped here. I'm working on an ASP.Net website that interacts with an SQL Server 2008 R2 database. So far everything has been going okay but updating a row (or more) just won't work. I even tried copying and pasting code from this site and others but it's always the same thing. In short: No exception or errors are shown when the update command executes (it even gives the correct count of affected rows) but no changes are actually made on the database. Here's a simplified version of my code (the original had more commands and tons of parameters each, but even when it's like this it doesn't work): protected void btSubmit_Click(object sender, EventArgs e) { using (SqlConnection connection = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString)) { string commandString = "UPDATE [impoundLotAlpha].[dbo].[Vehicle]" + "SET [VehicleMake] = @VehicleMake" + " WHERE [ComplaintID] = @ComplaintID"; using (SqlCommand command = new SqlCommand(commandString, connection)) { SqlTransaction transaction = null; try { command.Connection.Open(); transaction = connection.BeginTransaction(IsolationLevel.Serializable); command.Transaction = transaction; SqlParameter complaintID = new SqlParameter("@complaintID", SqlDbType.Int); complaintID.Value = HttpContext.Current.Request.QueryString["complaintID"]; command.Parameters.Add(complaintID); SqlParameter VehicleMake = new SqlParameter("@VehicleMake", SqlDbType.VarChar, 20); VehicleMake.Value = tbVehicleMake.Text; command.Parameters.Add(VehicleMake); command.ExecuteNonQuery(); transaction.Commit(); } catch { transaction.Rollback(); throw; } finally { connection.Close(); } } } } I've tried this with the "SqlTransaction" stuff and without it and nothing changes. Also, since I'm doing multiple updates at once, I want to have them act as a single transaction. I've found that it can be either done like this or by use of the classes included in the System.Transactions namespace (CommittableTransaction, TransactionScope...). I tried all I could find but didn't get any different results. The connection string in web.config is as follows: <connectionStrings> <add name="ApplicationServices" connectionString="Data Source=localhost;Initial Catalog=ImpoundLotAlpha;Integrated Security=True" providerName="System.Data.SqlClient"/> </connectionStrings> So, tldr; version: What is the mistake that I did with that record update attempt? (Figured it out, check below if you're having a similar issue.) What is the best method to gather multiple update commands as a single transaction? Thanks in advance for any kind of help and/or suggestions! Edit: It seems that I was lacking some sleep yesterday cause this time it only took me 5 minutes to figure out my mistake. Apparently the update was working properly but I failed to notice that the textbox values were being overwritten in Page_Load. For some reason I had this part commented: if (IsPostBack) return; The second part of the question still stands. But should I post this as an answer to my own question or keep it like this?

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HTML CheckBox labels within a container are not displayed as expected

- by Tiny

The following HTML code attempts to display checkboxes inside a <div></div> container. <div style="overflow: auto; width: auto; display:block; max-height:130px; max-width:200px; background-color: #FFF; height: auto; border: 1px double #336699; padding-left: 2px;"> <label for="chk12" style='white-space: nowrap;'> <input type='checkbox' id="chk12" name='chk_colours' value="12" class='validate[required] text-input text'> <div style='background-color:#FF8C00; width: 180px;' title="darkorange">  </div> </label> <label for="chk11" style='white-space: nowrap;'> <input type='checkbox' id="chk11" name='chk_colours' value="11" class='validate[required] text-input text'> <div style='background-color:#D9D919; width: 180px;' title="brightgold">  </div> </label> <label for="chk10" style='white-space: nowrap;'> <input type='checkbox' id="chk10" name='chk_colours' value="10" class='validate[required] text-input text'> <div style='background-color:#76EE00; width: 180px;' title="chartreuse2">  </div> </label> <label for="chk9" style='white-space: nowrap;'> <input type='checkbox' id="chk9" name='chk_colours' value="9" class='validate[required] text-input text'> <div style='background-color:#2E0854; width: 180px;' title="indigo">  </div> </label> <label for="chk8" style='white-space: nowrap;'> <input type='checkbox' id="chk8" name='chk_colours' value="8" class='validate[required] text-input text'> <div style='background-color:#292929; width: 180px;' title="gray16">  </div> </label> </div> What it displays can be visible in the following snap shot. It is seen that various colour stripes which are displayed using the following <div> tag <div style='background-color:#FF8C00; width: 180px;' title="darkorange"> &nbsp</div> are displayed below their respective checkboxes which are expected to be displayed in a straight line even though I'm using the white-space: nowrap; style attribute. How to display each stripe along with its respective checkbox in a straight line? It was explained in one of my questions itself but in that question each checkbox had a text label in place of such colour stripes. Here it is. I tried to do as mentioned in the accepted answer of that question but to no avail in this case.

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Why is my program getting slower and slower ?

- by RedWolf

I'm using the program to send data from database to the Excel file . It works fine at the beginning and then becomes more and more slowly,finally it run out of the memory and the following error ocurrs: "java.lang.OutOfMemoryError: Java heap space...". The problem can be resolved by adding the jvm heap sapce.But the question is that it spends too much time to run out the program. After several minutes,it finished a loop with 4 seconds which can be finished with 0.5 seconds at the beginning . I can't found a solution to make it always run in a certain speed. Is it my code problem? Any clues on this? Here is the code: public void addAnswerRow(List<FinalUsers> finalUsersList,WritableWorkbook book){ if (finalUsersList.size() >0 ) { try { WritableSheet sheet = book.createSheet("Answer", 0); int colCount = 0; sheet.addCell(new Label(colCount++,0,"Number")); sheet.addCell(new Label(colCount++,0,"SchoolNumber")); sheet.addCell(new Label(colCount++,0,"District")); sheet.addCell(new Label(colCount++,0,"SchoolName")); sheet.setColumnView(1, 15); sheet.setColumnView(3, 25); List<Elements> elementsList = this.elementsManager.getObjectElementsByEduTypeAndQuestionnaireType(finalUsersList.get(0).getEducationType().getId(), this.getQuestionnaireByFinalUsersType(finalUsersList.get(0).getFinalUsersType().getId())); Collections.sort(elementsList, new Comparator<Elements>(){ public int compare(Elements o1, Elements o2) { for(int i=0; i< ( o1.getItemNO().length()>o2.getItemNO().length()? o2.getItemNO().length(): o1.getItemNO().length());i++){ if (CommonFun.isNumberic(o1.getItemNO().substring(0, o1.getItemNO().length()>3? 4: o1.getItemNO().length()-1)) && !CommonFun.isNumberic(o2.getItemNO().substring(0, o2.getItemNO().length()>3? 4: o2.getItemNO().length()-1))){ return 1; } if (!CommonFun.isNumberic(o1.getItemNO().substring(0, o1.getItemNO().length()>3? 4: o1.getItemNO().length()-1)) && CommonFun.isNumberic(o2.getItemNO().substring(0,o2.getItemNO().length()>3? 4:o2.getItemNO().length()-1))){ return -1; } if ( o1.getItemNO().charAt(i)!=o2.getItemNO().charAt(i) ){ return o1.getItemNO().charAt(i)-o2.getItemNO().charAt(i); } } return o1.getItemNO().length()> o2.getItemNO().length()? 1:-1; }}); for (Elements elements : elementsList){ sheet.addCell(new Label(colCount++,0,this.getTitlePre(finalUsersList.get(0).getFinalUsersType().getId(), finalUsersList.get(0).getEducationType().getId())+elements.getItemNO()+elements.getItem().getStem())); } int sheetRowCount =1; int sheetColCount =0; for(FinalUsers finalUsers : finalUsersList){ sheetColCount =0; sheet.addCell(new Label(sheetColCount++,sheetRowCount,String.valueOf(sheetRowCount))); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getSchoolNumber())); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getDistrict().getDistrictNumber().toString().trim())); sheet.addCell(new Label(sheetColCount++,sheetRowCount,finalUsers.getSchool().getName())); List<AnswerLog> answerLogList = this.answerLogManager.getAnswerLogByFinalUsers(finalUsers.getId()); Map<String,String> answerMap = new HashMap<String,String>(); for(AnswerLog answerLog :answerLogList ){ if (answerLog.getOptionsId() != null) { answerMap.put(answerLog.getElement().getItemNO(), this.getOptionsAnswer(answerLog.getOptionsId())); }else if (answerLog.getBlanks()!= null){ answerMap.put(answerLog.getElement().getItemNO(), answerLog.getBlanks()); }else{ answerMap.put(answerLog.getElement().getItemNO(), answerLog.getSubjectiveItemContent()); } } for (Elements elements : elementsList){ sheet.addCell(new Label(sheetColCount++,sheetRowCount,null==answerMap.get(elements.getItemNO())?"0":answerMap.get(elements.getItemNO()))); } sheetRowCount++; } book.write(); book.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (RowsExceededException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (WriteException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

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"FOR UPDATE" v/s "LOCK IN SHARE MODE" : Allow concurrent threads to read updated "state" value of locked row

- by shadesco

I have the following scenario: User X logs in to the application from location lc1: call it Ulc1 User X (has been hacked, or some friend of his knows his login credential, or he just logs in from a different browser on his machine,etc.. u got the point) logs in at the same time from location lc2: call it Ulc2 I am using a main servlet which : - gets a connection from database pooling - sets autocommit to false - executes a command that goes through app layers: if all successful, set autocommit to true in a "finally" statement, and closes connection. Else if an exception happens, rollback(). In my database (mysql/innoDb) i have a "history" table, with row columns: id(primary key) |username | date | topic | locked The column "locked" has by default value "false" and it serves as a flag that marks if a specific row is locked or not. Each row is specific to a user (as u can see from the username column) So back to the scenario: --Ulc1 sends the command to update his history from the db for date "D" and topic "T". --Ulc2 sends the same command to update history from the db for the same date "D" and same topic "T" at the exact same time. I want to implement an mysql/innoDB locking system that will enable whichever thread arriving to do the following check: Is column "locked" for this row true or not? if true, return a message to the user that " he is already updating the same data from another location" if not true (ie not locked) : flag it as locked and update then reset locked to false once finished. Which of these two mysql locking techniques, will actually allow the 2nd arriving thread from reading the "updated" value of the locked column to decide wt action to take?Should i use "FOR UPDATE" or "LOCK IN SHARE MODE"? This scenario explains what i want to accomplish: - Ulc1 thread arrives first: column "locked" is false, set it to true and continue updating process - Ulc2 thread arrives while Ulc1's transaction is still in process, and even though the row is locked through innoDb functionalities, it doesn't have to wait but in fact reads the "new" value of column locked which is "true", and so doesn't in fact have to wait till Ulc1 transaction commits to read the value of the "locked" column(anyway by that time the value of this column will already have been reset to false). I am not very experienced with the 2 types of locking mechanisms, what i understand so far is that LOCK IN SHARE MODE allow other transaction to read the locked row while FOR UPDATE doesn't even allow reading. But does this read gets on the updated value? or the 2nd arriving thread has to wait the first thread to commit to then read the value? Any recommendations about which locking mechanism to use for this scenario is appreciated. Also if there's a better way to "check" if the row has been locked (other than using a true/false column flag) please let me know about it. thank you SOLUTION (Jdbc pseudocode example based on @Darhazer's answer) Table : [ id(primary key) |username | date | topic | locked ] connection.setautocommit(false); //transaction-1 PreparedStatement ps1 = "Select locked from tableName for update where id="key" and locked=false); ps1.executeQuery(); //transaction 2 PreparedStatement ps2 = "Update tableName set locked=true where id="key"; ps2.executeUpdate(); connection.setautocommit(true);// here we allow other transactions threads to see the new value connection.setautocommit(false); //transaction 3 PreparedStatement ps3 = "Update tableName set aField="Sthg" where id="key" And date="D" and topic="T"; ps3.executeUpdate(); // reset locked to false PreparedStatement ps4 = "Update tableName set locked=false where id="key"; ps4.executeUpdate(); //commit connection.setautocommit(true);

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C/PHP: How do I convert the following PHP JSON API script into a C plugin for apache?

- by TeddyB

I have a JSON API that I need to provide super fast access to my data through. The JSON API makes a simply query against the database based on the GET parameters provided. I've already optimized my database, so please don't recommend that as an answer. I'm using PHP-APC, which helps PHP by saving the bytecode, BUT - for a JSON API that is being called literally dozens of times per second (as indicated by my logs), I need to reduce the massive RAM consumption PHP is consuming ... as well as rewrite my JSON API in a language that execute much faster than PHP. My code is below. As you can see, is fairly straight forward. <?php define(ALLOWED_HTTP_REFERER, 'example.com'); if ( stristr($_SERVER['HTTP_REFERER'], ALLOWED_HTTP_REFERER) ) { try { $conn_str = DB . ':host=' . DB_HOST . ';dbname=' . DB_NAME; $dbh = new PDO($conn_str, DB_USERNAME, DB_PASSWORD); $params = array(); $sql = 'SELECT homes.home_id, address, city, state, zip FROM homes WHERE homes.display_status = true AND homes.geolat BETWEEN :geolatLowBound AND :geolatHighBound AND homes.geolng BETWEEN :geolngLowBound AND :geolngHighBound'; $params[':geolatLowBound'] = $_GET['geolatLowBound']; $params[':geolatHighBound'] = $_GET['geolatHighBound']; $params[':geolngLowBound'] =$_GET['geolngLowBound']; $params[':geolngHighBound'] = $_GET['geolngHighBound']; if ( isset($_GET['min_price']) && isset($_GET['max_price']) ) { $sql = $sql . ' AND homes.price BETWEEN :min_price AND :max_price '; $params[':min_price'] = $_GET['min_price']; $params[':max_price'] = $_GET['max_price']; } if ( isset($_GET['min_beds']) && isset($_GET['max_beds']) ) { $sql = $sql . ' AND homes.num_of_beds BETWEEN :min_beds AND :max_beds '; $params['min_beds'] = $_GET['min_beds']; $params['max_beds'] = $_GET['max_beds']; } if ( isset($_GET['min_sqft']) && isset($_GET['max_sqft']) ) { $sql = $sql . ' AND homes.sqft BETWEEN :min_sqft AND :max_sqft '; $params['min_sqft'] = $_GET['min_sqft']; $params['max_sqft'] = $_GET['max_sqft']; } $stmt = $dbh->prepare($sql); $stmt->execute($params); $result_set = $stmt->fetchAll(PDO::FETCH_ASSOC); /* output a JSON representation of the home listing data retrieved */ ob_start("ob_gzhandler"); // compress the output header('Content-type: text/javascript'); print "{'homes' : "; array_walk_recursive($result_set, "cleanOutputFromXSS"); print json_encode( $result_set ); print '}'; $dbh = null; } catch (PDOException $e) { die('Unable to retreive home listing information'); } } function cleanOutputFromXSS(&$value) { $value = htmlspecialchars($value, ENT_QUOTES, 'UTF-8'); } ?> How would I begin converting this PHP code over to C, since C is both better on memory management (since you do it yourself) and much, much faster to execute?

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What's the fastest lookup algorithm for a pair data structure (i.e, a map)?

- by truncheon

In the following example a std::map structure is filled with 26 values from A - Z (for key) and 0 – 26 for value. The time taken (on my system) to lookup the last entry (10000000 times) is roughly 250 ms for the vector, and 125 ms for the map. (I compiled using release mode, with O3 option turned on for g++ 4.4) But if for some odd reason I wanted better performance than the std::map, what data structures and functions would I need to consider using? I apologize if the answer seems obvious to you, but I haven't had much experience in the performance critical aspects of C++ programming. UPDATE: This example is rather trivial and hides the true complexity of what I'm trying to achieve. My real world project is a simple scripting language that uses a parser, data tree, and interpreter (instead of a VM stack system). I need to use some kind of data structure (perhaps map) to store the variables names created by script programmers. These are likely to be pretty randomly named, so I need a lookup method that can quickly find a particular key within a (probably) fairly large list of names. #include <ctime> #include <map> #include <vector> #include <iostream> struct mystruct { char key; int value; mystruct(char k = 0, int v = 0) : key(k), value(v) { } }; int find(const std::vector<mystruct>& ref, char key) { for (std::vector<mystruct>::const_iterator i = ref.begin(); i != ref.end(); ++i) if (i->key == key) return i->value; return -1; } int main() { std::map<char, int> mymap; std::vector<mystruct> myvec; for (int i = 'a'; i < 'a' + 26; ++i) { mymap[i] = i - 'a'; myvec.push_back(mystruct(i, i - 'a')); } int pre = clock(); for (int i = 0; i < 10000000; ++i) { find(myvec, 'z'); } std::cout << "linear scan: milli " << clock() - pre << "\n"; pre = clock(); for (int i = 0; i < 10000000; ++i) { mymap['z']; } std::cout << "map scan: milli " << clock() - pre << "\n"; return 0; }

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SSRS 2008 printing single page renders different for print

- by user270437

I have a problem with SSRS 2008 reports rendering differently on the reporting server than the way it renders when you print the report. I’m trying to figure out to print a single page and have the print show that same records as I see on the report on the screen. As a test, I created a simple report with no headers or footers and just added a Tablix table to display the records (no groupings). My data set for this test displays 2 ¼ pages of records when I deploy it to our reporting services server and run it. If I click the print Icon and preview the report is 2 ¾ pages. I haven’t found anything searching on this so it makes me think it is something simple I’m missing. A basically want the report to render the same records on each page in Report Manager as it does when it prints, how do I accomplish this? (In response to answer posted by Chris)…If that is the case then it is disappointing. Customers are accustomed to WYSIWYG and will have a hard time understanding that, I imagine we will be getting a lot of support calls. This still leaves an issue. I tried using print preview and could not find any way to single out a page. If I select a page up front to print, or preview it renders different so I get different records. And if I preview the entire document, I can only print the entire document. You mentioned the Excel render; we have customers that will want that also. The problem I have found with Excel exports is that even a basic report winds up merging some cells and that messes up sorting. I’m going to try your tip about grouping to see if I can get a clean export to a page. It would have been nice if they would have created a property for certain controls like the tablix table called “ExcelSheet”. Then all you would have to do is give it a name and it would create a new sheet for each control with a name, the name becoming the sheet title. Thanks for the information you supplied it is very useful as I’m new to SSRS. If you know how I can Preview in print render and select individual pages to print from the render let me know. Update 02/19/2010 After testing this more I now realize it is just a bad design of Report managers print driver or a limitation because it is server based. The options work differently than Windows apps drivers, But I did find a work around. Here is the test I performed comparing Excel to Report Manager. I bring up a report that will render more than 1 page when printed. I then export to Excel, in Excel I select print preview. I can navigate the pages in preview and then select a single page like page 3. I can then print just page 3 without leaving print preview and it prints just like it rendered. I cannot do this using print in report manager. If I select print preview in report manager then try to print while in preview it always prints the entire document. However if I close out of print preview, I can then select page 3 and print it as rendered. It is just one additional step once you know what to do, but it took some time to figure it out.

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Extending JavaScript's Date.parse to allow for DD/MM/YYYY (non-US formatted dates)?

- by Campbeln

I've come up with this solution to extending JavaScript's Date.parse function to allow for dates formatted in DD/MM/YYYY (rather then the American standard [and default] MM/DD/YYYY): (function() { var fDateParse = Date.parse; Date.parse = function(sDateString) { var a_sLanguage = ['en','en-us'], a_sMatches = null, sCurrentLanguage, dReturn = null, i ; //#### Traverse the a_sLanguages (as reported by the browser) for (i = 0; i < a_sLanguage.length; i++) { //#### Collect the .toLowerCase'd sCurrentLanguage for this loop sCurrentLanguage = (a_sLanguage[i] + '').toLowerCase(); //#### If this is the first English definition if (sCurrentLanguage.indexOf('en') == 0) { //#### If this is a definition for a non-American based English (meaning dates are "DD MM YYYY") if (sCurrentLanguage.indexOf('en-us') == -1 && // en-us = English (United States) + Palau, Micronesia, Philippians sCurrentLanguage.indexOf('en-ca') == -1 && // en-ca = English (Canada) sCurrentLanguage.indexOf('en-bz') == -1 // en-bz = English (Belize) ) { //#### Setup a oRegEx to locate "## ## ####" (allowing for any sort of delimiter except a '\n') then collect the a_sMatches from the passed sDateString var oRegEx = new RegExp("(([0-9]{2}|[0-9]{1})[^0-9]*?([0-9]{2}|[0-9]{1})[^0-9]*?([0-9]{4}))", "i"); a_sMatches = oRegEx.exec(sDateString); } //#### Fall from the loop (as we've found the first English definition) break; } } //#### If we were able to find a_sMatches for a non-American English "DD MM YYYY" formatted date if (a_sMatches != null) { var oRegEx = new RegExp(a_sMatches[0], "i"); //#### .parse the sDateString via the normal Date.parse function, but replacing the "DD?MM?YYYY" with "YYYY/MM/DD" beforehand //#### NOTE: a_sMatches[0]=[Default]; a_sMatches[1]=DD?MM?YYYY; a_sMatches[2]=DD; a_sMatches[3]=MM; a_sMatches[4]=YYYY dReturn = fDateParse(sDateString.replace(oRegEx, a_sMatches[4] + "/" + a_sMatches[3] + "/" + a_sMatches[2])); } //#### Else .parse the sDateString via the normal Date.parse function else { dReturn = fDateParse(sDateString); } //#### return dReturn; } })(); In my actual (dotNet) code, I'm collecting the a_sLanguage array via: a_sLanguage = '<% Response.Write(Request.ServerVariables["HTTP_ACCEPT_LANGUAGE"]); %>'.split(','); Now, I'm not certain my approach to locating "us-en"/etc. is the most proper. Pretty much it's just the US and current/former US influenced areas (Palau, Micronesia, Philippines) + Belize & Canada that use the funky MM/DD/YYYY format (I am American, so I can call it funky =). So one could rightly argue that if the Locale is not "en-us"/etc. first, then DD/MM/YYYY should be used. Thoughts? As a side note... I "grew up" in PERL but it's been a wee while since I've done much heavy lifting in RegEx. Does that expression look right to everyone? This seems like a lot of work, but based on my research this is indeed about the best way to go about enabling DD/MM/YYYY dates within JavaScript. Is there an easier/more betterer way? PS- Upon re-reading this post just before submission... I've realized that this is more of a "can you code review this" rather then a question (or, an answer is embedded within the question). When I started writing this it was not my intention to end up here =)

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Mallocing an unsigned char array to store ints

- by Max Desmond

I keep getting a segmentation fault when i test the following code. I am currently unable to find an answer after having searched the web. a = (byte *)malloc(sizeof(byte) * x ) ; for( i = 0 ; i < x-1 ; i++ ) { scanf("%d", &y ) ; a[i] = y ; } Both y and x are initialized. X is the size of the array determined by the user. The segmentation fault is on the second to last integer to be added, i found this by adding printf("roar") ; before setting a[i] to y and entering one number at a time. Byte is a typedef of an unsigned char. Note: I've also tried using a[i] = (byte)y ; A is ininitalized as follows byte *a ; If you need to view the entire code it is this: #include <stdio.h> #include <stdlib.h> #include "sort.h" int p_cmp_f () ; int main( int argc, char *argv[] ) { int x, y, i, choice ; byte *a ; while( choice !=2 ) { printf( "Would you like to sort integers?\n1. Yes\n2. No\n" ) ; scanf("%d", &choice ) ; switch(choice) { case 1: printf( "Enter the length of the array: " ) ; scanf( "%d", &x ) ; a = (byte *)malloc(sizeof( byte ) * x ) ; printf( "Enter %d integers to add to the array: ", x ) ; for( i = 0 ; i < x -1 ; i++ ) { scanf( "%d", &y ) ; a[i] = y ; } switch( choice ) { case 1: bubble_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; case 2: selection_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x; i++ ) printf( "%d", a[i] ; break ; case 3: insertion_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; case 4: merge_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; case 5: quick_sort( a, x, sizeof(int), p_cmp_f ) ; for( i = 0 ; i < x ; i++ ) printf( "%d", a[i] ; break ; default: printf("Enter either 1,2,3,4, or 5" ) ; break ; } case 2: printf( "Thank you for using this program\n" ) ; return 0 ; break ; default: printf( "Enter either 1 or 2: " ) ; break ; } } free(a) ; return 0 ; } int p_cmp_f( byte *element1, byte *element2 ) { return *((int *)element1) - *((int *)element2) ; }

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Same source, multiple targets with different resources (Visual Studio .Net 2008)

- by Mike Bell

A set of software products differ only by their resource strings, binary resources, and by the strings / graphics / product keys used by their Visual Studio Setup projects. What is the best way to create, organize, and maintain them? i.e. All the products essentially consist of the same core functionality customized by graphics, strings, and other resource data to form each product. Imagine you are creating a set of products like "Excel for Bankers", Excel for Gardeners", "Excel for CEOs", etc. Each product has the the same functionality, but differs in name, graphics, help files, included templates etc. The environment in which these are being built is: vanilla Windows.Forms / Visual Studio 2008 / C# / .Net. The ideal solution would be easy to maintain. e.g. If I introduce a new string / new resource projects I haven't added the resource to should fail at compile time, not run time. (And subsequent localization of the products should also be feasible). Hopefully I've missed the blindingly-obvious and easy way of doing all this. What is it? ============ Clarification(s) ================ By "product" I mean the package of software that gets installed by the installer and sold to the end user. Currently I have one solution, consisting of multiple projects, (including a Setup project), which builds a set of assemblies and create a single installer. What I need to produce are multiple products/installers, all with similar functionality, which are built from the same set of assemblies but differ in the set of resources used by one of the assemblies. What's the best way of doing this? ------------ The 95% Solution ----------------- Based upon Daminen_the_unbeliever's answer, a resource file per configuration can be achieved as follows: Create a class library project ("Satellite"). Delete the default .cs file and add a folder ("Default") Create a resource file in the folder "MyResources" Properties - set CustomToolNamespace to something appropriate (e.g. "XXX") Make sure the access modifier for the resources is "Public". Add the resources. Edit the source code. Refer to the resources in your code as XXX.MyResources.ResourceName) Create Configurations for each product variant ("ConfigN") For each product variant, create a folder ("VariantN") Copy and Paste the MyResources file into each VariantN folder Unload the "Satellite" project, and edit the .csproj file For each "VariantN/MyResources" <Compile> or <EmbeddedResource> tag, add a Condition="'$(Configuration)' == 'ConfigN'" attribute. Save, Reload the .csproj, and you're done... This creates a per-configuration resource file, which can (presumably) be further localized. Compile error messages are produced for any configuration that where a a resource is missing. The resource files can be localized using the standard method (create a second resources file (MyResources.fr.resx) and edit .csproj as before). The reason this is a 95% solution is that resources used to initialize forms (e.g. Form Titles, button texts) can't be easily handled in the same manner - the easiest approach seems to be to overwrite these with values from the satellite assembly.

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UIPageViewController blanking page

- by CrazyEoin

I've been trying to use the UIPageViewController to display 3 different nibs for a few days on and off now and have almost got it working. I still have one weird bug that I cant figure out. Basically the app starts, I can scroll between the 3 pages one after another with out any problems, eg: Page1-Page2-Page3 and then back to the start: Page3-Page2-Page1. No Problems. The issue is that if I scroll, for example from Page3-Page2, then BACK to Page3, Page3 Dissappears when it snaps into place. If I scroll to where a forth page would be, then I get Page3. Here is the code relevant to the UIPageViewController, the nibs and the delegate methods for the UIPageViewController: - (void)viewDidLoad{ [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil]; self.pageViewController.delegate = self; [[self.pageViewController view] setFrame:[[self view] bounds]]; indexTest = 0; Page1 *p1 = [[Page1 alloc]initWithNibName:@"Page1" bundle:nil]; p1.view.tag = 1; Page2 *p2 = [[Page2 alloc]initWithNibName:@"Page2" bundle:nil]; p2.view.tag = 2; Page3 *p3 = [[Page3 alloc]initWithNibName:@"Page3" bundle:nil]; p3.view.tag = 3; NSArray *arr = [[NSArray alloc] initWithObjects:p1,nil]; viewControllers = [[NSMutableArray alloc] initWithObjects:p1,p2,p3, nil]; [self.pageViewController setViewControllers:arr direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil]; self.pageViewController.dataSource = self; [self addChildViewController:self.pageViewController]; [[self view] addSubview:[self.pageViewController view]]; [self.pageViewController didMoveToParentViewController:self]; self.view.gestureRecognizers = self.pageViewController.gestureRecognizers; } #pragma mark - page view controller stuff - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController { if (indexTest > 0) { switch (indexTest) { case 1:{ NSLog(@"NO page is BEFORE current page"); break; } case 2:{ NSLog(@"Page BEFORE is Page: %@", [NSString stringWithFormat:@"%@",[viewControllers objectAtIndex:0] ] ); indexTest--; return [viewControllers objectAtIndex:0]; break; } default:{ NSLog(@"PROBLEM in viewBEFORE, indexTest = %d!!!!", indexTest); break; } } } return nil; } - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController { if (indexTest < NUM_OF_PAGES) { switch (indexTest) { case 0:{ NSLog(@"Page AFTER is Page: %@", [NSString stringWithFormat:@"%@",[viewControllers objectAtIndex:1] ] ); indexTest++; return [viewControllers objectAtIndex:1]; break; } case 1:{ NSLog(@"Page AFTER is Page: %@", [NSString stringWithFormat:@"%@",[viewControllers objectAtIndex:2] ] ); indexTest++; return [viewControllers objectAtIndex:2]; break; } case 2:{ NSLog(@"No pages AFTER this current page %d", indexTest); break; } default:{ NSLog(@"PROBLEM in viewAFTER, indexTest = %d!!!!", indexTest); break; } } } return nil; } Finally the page index dots code #pragma mark - dot controller - (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController { // The number of items reflected in the page indicator. return NUM_OF_PAGES; } - (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController { // The selected item reflected in the page indicator. return 0; } Any and all help is much appreciated, I think I'm just doing something silly that I cant see as I'm so close to it fully working. If anythings not clear or I haven't give enough information please let me know and I'll answer it as best as I can. Thanks

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Double Linked List header node keeps returning first value as 0

- by Craig

I will preface to say that this is my first question. I am currently getting my Masters degree in Information Security and I had to take C++ programming this semester. So this is homework related. I am not looking for you to answer my homework but I am running into a peculiar situation. I have created the program to work with a doubly linked list and everything works fine. However when I have the user create a list of values the first node keeps returning 0. I have tried finding some reading on this and I cannot locate any reference to it. My question is then is the header node(first node) always going to be zero? Or am I doing something wrong. case: 'C': cout<<"Please enter a list:"<<endl; while(n!=-999){ myList.insert(n); cin>> n;} break; I now enter: 12321, 1234,64564,346346. The results in 0, 12321, 1234, 64564,346346. Is this what should happen or am I doing something wrong? Also as this is my first post please feel free to criticize or teach me how to color code the keywords. Anyway this is a homework assignment so I am only looking for guidance and constructive criticism. Thank you all in advance So I cannot figure out the comment sections on this forum so I will edit the original post The first section is the constructor code: template <class Type> doublyLinkedList<Type>::doublyLinkedList() { first= NULL; last = NULL; count = 0; } Then there is my insert function : template <class Type> void doublyLinkedList<Type>::insert(const Type& insertItem) { nodeType<Type> *current; //pointer to traverse the list nodeType<Type> *trailCurrent; //pointer just before current nodeType<Type> *newNode; //pointer to create a node bool found; newNode = new nodeType<Type>; //create the node newNode->info = insertItem; //store the new item in the node newNode->next = NULL; newNode->back = NULL; if(first == NULL) //if the list is empty, newNode is //the only node { first = newNode; last = newNode; count++; } else { found = false; current = first; while (current != NULL && !found) //search the list if (current->info >= insertItem) found = true; else { trailCurrent = current; current = current->next; } if (current == first) //insert newNode before first { first->back = newNode; newNode->next = first; first = newNode; count++; } else { //insert newNode between trailCurrent and current if (current != NULL) { trailCurrent->next = newNode; newNode->back = trailCurrent; newNode->next = current; current->back = newNode; } else { trailCurrent->next = newNode; newNode->back = trailCurrent; last = newNode; } count++; }//end else }//end else }//end Then I have an initialization function too: template <class Type> void doublyLinkedList<Type>::initializeList() { destroy(); } Did I miss anything?

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SOAP Service Request C#

- by user3728352

I have this code that tries to send a request to a soap server, I'm new to soap so i am not sure if the terms i am using are correct or not please correct me I am wrong. Basically i am accessing a web service method named getUserDomain via soap request Here is the code: public void CallWebService() { var _url = "https://....com/QcXmlWebService/QcXmlWebService.asmx?wsdl"; var _action = "https://....com/QcXmlWebService/QcXmlWebService.asmx?op=GetUserDomains"; XmlDocument soapEnvelopeXml = CreateSoapEnvelope(); HttpWebRequest webRequest = CreateWebRequest(_url, _action); InsertSoapEnvelopeIntoWebRequest(soapEnvelopeXml, webRequest); webRequest.BeginGetResponse(null, null); // begin async call to web request. IAsyncResult asyncResult = webRequest.BeginGetResponse(null, null); // suspend this thread until call is complete. You might want to // do something usefull here like update your UI. asyncResult.AsyncWaitHandle.WaitOne(); // get the response from the completed web request. string soapResult; using (WebResponse webResponse = webRequest.EndGetResponse(asyncResult)) { using (StreamReader rd = new StreamReader(webResponse.GetResponseStream())) { soapResult = rd.ReadToEnd(); } Console.Write(soapResult); } } private HttpWebRequest CreateWebRequest(string url, string action) { HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url); webRequest.Headers.Add("SOAPAction", action); webRequest.ContentType = "text/xml;charset=\"utf-8\""; webRequest.Accept = "text/xml"; webRequest.Method = "POST"; return webRequest; } private XmlDocument CreateSoapEnvelope() { XmlDocument soapEnvelop = new XmlDocument(); string oRequest = ""; oRequest = @"<soap:Envelope xmlns:soap=""http://www.w3.org/2003/05/soap-envelope"" xmlns:qcx=""http://smething.com/QCXML"">"; oRequest = oRequest + "<soap:Header/>"; oRequest = oRequest + "<soap:Body>"; oRequest = oRequest + "<qcx:GetUserDomains>"; oRequest = oRequest + "<qcx:inputXml><![CDATA["; oRequest = oRequest + "<GetUserDomains>"; oRequest = oRequest + "<login>"; oRequest = oRequest + "<domain_name>MBB_BTS</domain_name>"; oRequest = oRequest + "<project_name>WCDMA_BTS_IV</project_name>"; oRequest = oRequest + "<user_name>user</user_name>"; oRequest = oRequest + "<password>pass</password>"; oRequest = oRequest + "</login>"; oRequest = oRequest + "</GetUserDomains>"; oRequest = oRequest + " ]]>"; oRequest = oRequest + "</qcx:inputXml>"; oRequest = oRequest + "</qcx:GetUserDomains>"; oRequest = oRequest + "</soap:Body>"; oRequest = oRequest + "</soap:Envelope>"; soapEnvelop.LoadXml(oRequest); return soapEnvelop; } private void InsertSoapEnvelopeIntoWebRequest(XmlDocument soapEnvelopeXml, HttpWebRequest webRequest) { using (Stream stream = webRequest.GetRequestStream()) { soapEnvelopeXml.Save(stream); } } This code i have seen somewhere in stack overflow before as an answer but i couldn't get it to work... The error im getting is threw exception System.net.webexception. the remote server returned an error :(500) internal server Thanks

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How to force a page refresh or reload in jQuery?

- by TimMac

The code below displays a google map and search results when you enter an address and hit the submit button. I've been playing with it to try and force the page to completely refresh or reload once you hit the submit button. But I can't get it to work right. It loads the results "in page," but I'd like the page to completely refresh when the results load, like when you hit the back button on your browser. Hope that makes sense. I think the answer lies in this line of code but I don't know jquery very well. It's near the bottom of the full code below. <script type="text/javascript"> (function($) { $(document).ready(function() { load();'; Here's the full code below. Any help would be greatly appreciated! <?php /* SimpleMap Plugin display-map.php: Displays the Google Map and search results */ $to_display = ''; if ($options['display_search'] == 'show') { $to_display .= ' <div id="map_search" style="width: '.$options['map_width'].';"> <a name="map_top"></a> <form onsubmit="searchLocations(\''.$categories.'\'); return false;" name="searchForm" id="searchForm" action="http://'.$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'].'"> <input type="text" id="addressInput" name="addressInput" class="address" />  <select name="radiusSelect" id="radiusSelect">'; $default_radius = $options['default_radius']; unset($selected_radius); $selected_radius[$default_radius] = ' selected="selected"'; foreach ($search_radii as $value) { $r = (int)$value; $to_display .= '<option valu e="'.$value.'"'.$selected_radius[$r].'>'.$value.' '.$options['units']."</option>\n"; } $to_display .= ' </select>  <input type="submit" value="'.__('Search', 'SimpleMap').'" id="addressSubmit" class="submit" /> <p>'.__('Please enter an address or search term in the box above.', 'SimpleMap').'</p> </form> </div>'; } if ($options['powered_by'] == 'show') { $to_display .= '<div id="powered_by_simplemap">'.sprintf(__('Powered by %s SimpleMap', 'SimpleMap'),'<a href="http://simplemap-plugin.com/" target="_blank">').'</a></div>'; } $to_display .= ' <div id="map" style="width: '.$options['map_width'].'; height: '.$options['map_height'].';"></div> <div id="results" style="width: '.$options['map_width'].';"></div> <script type="text/javascript"> (function($) { $(document).ready(function() { load();'; if ($options['autoload'] == 'some') { $to_display .= 'var autoLatLng = new GLatLng(default_lat, default_lng); searchLocationsNear(autoLatLng, autoLatLng.lat() + ", " + autoLatLng.lng(), "auto", "'.$options['lock_default_location'].'", "'.$categories.'");'; } else if ($options['autoload'] == 'all') { $to_display .= 'var autoLatLng = new GLatLng(default_lat, default_lng); searchLocationsNear(autoLatLng, autoLatLng.lat() + ", " + autoLatLng.lng(), "auto_all", "'.$options['lock_default_location'].'", "'.$categories.'");'; } $to_display .= ' }); })(jQuery); </script>'; ?>

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Is this a reasonable way to handle getters/setters in a PHP class?

- by Mark Biek

I'm going to try something with the format of this question and I'm very open to suggestions about a better way to handle it. I didn't want to just dump a bunch of code in the question so I've posted the code for the class on refactormycode. base-class-for-easy-class-property-handling My thought was that people can either post code snippets here or make changes on refactormycode and post links back to their refactorings. I'll make upvotes and accept an answer (assuming there's a clear "winner") based on that. At any rate, on to the class itself: I see a lot of debate about getter/setter class methods and is it better to just access simple property variables directly or should every class have explicit get/set methods defined, blah blah blah. I like the idea of having explicit methods in case you have to add more logic later. Then you don't have to modify any code that uses the class. However I hate having a million functions that look like this: public function getFirstName() { return $this->firstName; } public function setFirstName($firstName) { return $this->firstName; } Now I'm sure I'm not the first person to do this (I'm hoping that there's a better way of doing it that someone can suggest to me). Basically, the PropertyHandler class has a __call magic method. Any methods that come through __call that start with "get" or "set" are then routed to functions that set or retrieve values into an associative array. The key into the array is the name of the calling method after get or set. So, if the method coming into __call is "getFirstName", the array key is "FirstName". I liked using __call because it will automatically take care of the case where the subclass already has a "getFirstName" method defined. My impression (and I may be wrong) is that the __get & __set magic methods don't do that. So here's an example of how it would work: class PropTest extends PropertyHandler { public function __construct() { parent::__construct(); } } $props = new PropTest(); $props->setFirstName("Mark"); echo $props->getFirstName(); Notice that PropTest doesn't actually have "setFirstName" or "getFirstName" methods and neither does PropertyHandler. All that's doing is manipulating array values. The other case would be where your subclass is already extending something else. Since you can't have true multiple inheritance in PHP, you can make your subclass have a PropertyHandler instance as a private variable. You have to add one more function but then things behave in exactly the same way. class PropTest2 { private $props; public function __construct() { $this->props = new PropertyHandler(); } public function __call($method, $arguments) { return $this->props->__call($method, $arguments); } } $props2 = new PropTest2(); $props2->setFirstName('Mark'); echo $props2->getFirstName(); Notice how the subclass has a __call method that just passes everything along to the PropertyHandler __call method. Another good argument against handling getters and setters this way is that it makes it really hard to document. In fact, it's basically impossible to use any sort of document generation tool since the explicit methods to be don't documented don't exist. I've pretty much abandoned this approach for now. It was an interesting learning exercise but I think it sacrifices too much clarity.

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if statement to check available elements

- by nicmare

Hi there, i allways found an answer here just be reading the threads but now its time for my very first thread because i was unable to find related questions: this is my target code: <li> <span class="panel"> <a href="…" class="image" rel="group"> <img title="…" src="…" alt="…" width="128" height="96" /> </a> <span class="sizes"> <span class="button"> <a href="#" class="size1" rel="…" title="1">9x13</a> </span> <span class="button"> <a href="#" class="size2" rel="…" title="3">10x15</a> </span> <span class="button"> <a href="#" class="size3" rel="…" title="6">20x30</a> </span> </span> </span> <a href="…" class="image" rel="group"> <span class="added"></span> <img title="…" src="…" alt="…" width="128" height="96" class="thumbnail" /> </a> </li> i add two "span" elements through jquery: $('.sizes a').click( function (e) { e.preventDefault(); $(this).after("<span class='checked'></span><span class='remove'></span>"); } ); the maximum amount of those s are 3 times in a wrapped div. so i am trying to do is the following: $(".remove").live('click', function(){ $(this).hide(); $(this).prev().hide(); // hide checked span if ($(this).parent().parent().children().children().each().hasClass('checked')) { $(this).parent().parent().parent().next().children(".added").hide(); } } ); of course my if statement is crap. i try it in my own words: if there are more than one span(class=remove) in span(class=panel) then nothing should happen. but if there is just one span(class=remove) left in span(class=panel) THEN should be hidden how do i achieve this? there is an online demonstration of this: http://bit.ly/972be4 as you can see, every time when i hit a button below an image, the image gets marked by a label. and i want to hide this label (class=added) when no button is selected Thank you very much! best wishes from germany

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Testing shared memory ,strange thing happen

- by barfatchen

I have 2 program compiled in 4.1.2 running in RedHat 5.5 , It is a simple job to test shared memory , shmem1.c like following : #define STATE_FILE "/program.shared" #define NAMESIZE 1024 #define MAXNAMES 100 typedef struct { char name[MAXNAMES][NAMESIZE]; int heartbeat ; int iFlag ; } SHARED_VAR; int main (void) { int first = 0; int shm_fd; static SHARED_VAR *conf; if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_EXCL | O_RDWR), (S_IREAD | S_IWRITE))) > 0 ) { first = 1; /* We are the first instance */ } else if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_RDWR), (S_IREAD | S_IWRITE))) < 0) { printf("Could not create shm object. %s\n", strerror(errno)); return errno; } if((conf = mmap(0, sizeof(SHARED_VAR), (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0)) == MAP_FAILED) { return errno; } if(first) { for(idx=0;idx< 1000000000;idx++) { conf->heartbeat = conf->heartbeat + 1 ; } } printf("conf->heartbeat=(%d)\n",conf->heartbeat) ; close(shm_fd); shm_unlink(STATE_FILE); exit(0); }//main And shmem2.c like following : #define STATE_FILE "/program.shared" #define NAMESIZE 1024 #define MAXNAMES 100 typedef struct { char name[MAXNAMES][NAMESIZE]; int heartbeat ; int iFlag ; } SHARED_VAR; int main (void) { int first = 0; int shm_fd; static SHARED_VAR *conf; if((shm_fd = shm_open(STATE_FILE, (O_RDWR), (S_IREAD | S_IWRITE))) < 0) { printf("Could not create shm object. %s\n", strerror(errno)); return errno; } ftruncate(shm_fd, sizeof(SHARED_VAR)); if((conf = mmap(0, sizeof(SHARED_VAR), (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0)) == MAP_FAILED) { return errno; } int idx ; for(idx=0;idx< 1000000000;idx++) { conf->heartbeat = conf->heartbeat + 1 ; } printf("conf->heartbeat=(%d)\n",conf->heartbeat) ; close(shm_fd); exit(0); } After compiled : gcc shmem1.c -lpthread -lrt -o shmem1.exe gcc shmem2.c -lpthread -lrt -o shmem2.exe And Run both program almost at the same time with 2 terminal : [test]$ ./shmem1.exe First creation of the shm. Setting up default values conf->heartbeat=(840825951) [test]$ ./shmem2.exe conf->heartbeat=(1215083817) I feel confused !! since shmem1.c is a loop 1,000,000,000 times , how can it be possible to have a answer like 840,825,951 ? I run shmem1.exe and shmem2.exe this way,most of the results are conf-heartbeat will larger than 1,000,000,000 , but seldom and randomly , I will see result conf-heartbeat will lesser than 1,000,000,000 , either in shmem1.exe or shmem2.exe !! if run shmem1.exe only , it is always print 1,000,000,000 , my question is , what is the reason cause conf-heartbeat=(840825951) in shmem1.exe ? Update: Although not sure , but I think I figure it out what is going on , If shmem1.exe run 10 times for example , then conf-heartbeat = 10 , in this time shmem1.exe take a rest and then back , shmem1.exe read from shared memory and conf-heartbeat = 8 , so shmem1.exe will continue from 8 , why conf-heartbeat = 8 ? I think it is because shmem2.exe update the shared memory data to 8 , shmem1.exe did not write 10 back to shared memory before it took a rest ....that is just my theory... i don't know how to prove it !!

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How To Run XP Mode in VirtualBox on Windows 7 (sort of)

- by Matthew Guay

A few weeks ago we showed you how to run XP Mode on a Windows 7 computer without Hardware Virtualization using VMware. Some of you have been asking if it can be done in Virtual Box as well. The answer is “Yes!” and here we’ll show you how. Editor Update: Apparently there isn’t a way to activate XP Mode through VirtualBox using this method. You will however, be able to run it for 30 days. We have a new updated article on how to Install XP Mode with VirtualBox Using the VMLite Plugin. Earlier we showed you how to run XP mode on windows 7 machines without hardware virtualization capability. Since then, a lot of you have been asking to a write up a tutorial about doing the same thing using VirtualBox. This makes it another great way to run XP Mode if your computer does not have hardware virtualization. Here we’ll see how to import the XP Mode from Windows 7 Professional, Enterprise, or Ultimate into VirtualBox so you can run XP in it for free. Note: You need to have Windows 7 Professional or above to use XP Mode in this manner. In our tests we were able to get it to run on Home Premium as well, but you’ll be breaking Windows 7 licensing agreements. Getting Started First, download and install XP Mode (link below). There is no need to download Virtual PC if your computer cannot run it, so just download the XP Mode from the link on the left. Install XP mode; just follow the default prompts as usual. Now, download and install VirtualBox 3.1.2 or higher(link below). Install as normal, and simply follow the default prompts. VirtualBox may notify you that your network connection will be reset during the installation. Press Yes to continue. During the install, you may see several popups asking you if you wish to install device drivers for USB and Network interfaces. Simply click install, as these are needed for VirtualBox to run correctly. Setup only took a couple minutes, and doesn’t require a reboot. Setup XP Mode in VirtualBox: First we need to copy the default XP Mode so VirtualBox will not affect the original copy. Browse to C:\Program Files\Windows XP Mode, and copy the file “Windows XP Mode base.vhd”. Paste it in another folder of your choice, such as your Documents folder. Once you’ve copied the file, right-click on it and click Properties. Uncheck the “Read-only” box in this dialog, and then click Ok. Now, in VirtualBox, click New to create a new virtual machine. Enter the name of your virtual machine, and make sure the operating system selected is Windows XP. Choose how much memory you want to allow the virtual machine to use. VirtualBox’ default is 192 Mb ram, but for better performance you can select 256 or 512Mb. Now, select the hard drive for the virtual machine. Select “Use existing hard disk”, then click the folder button to choose the XP Mode virtual drive. In this window, click Add, and then browse to find the copy of XP Mode you previously made. Make sure the correct virtual drive is selected, then press Select. After selecting the VHD your screen should look like the following then click Next. Verify the settings you made are correct. If not, you can go back and make any changes. When everything looks correct click Finish. Setup XP Mode Now, in VirtualBox, click start to run XP Mode. The Windows XP in this virtual drive is not fully setup yet, so you will have to go through the setup process. If you didn’t uncheck the “Read-only” box in the VHD properties before, you may see the following error. If you see it, go back and check the file to makes sure it is not read-only. When you click in the virtual machine, it will capture your mouse by default. Simply press the right Ctrl key to release your mouse so you can go back to using Windows 7. This will only be the case during the setup process; after the Guest Additions are installed, the mouse will seamlessly move between operating systems. Now, accept the license agreement in XP. Choose your correct locale and keyboard settings. Enter a name for your virtual XP, and an administrative password. Check the date, time, and time zone settings, and adjust them if they are incorrect. The time and date are usually correct, but the time zone often has to be corrected. XP will now automatically finish setting up your virtual machine, and then will automatically reboot. After rebooting, select your automatic update settings. You may see a prompt to check for drivers; simply press cancel, as all the drivers we need will be installed later with the Guest Additions. Your last settings will be finalized, and finally you will see your XP desktop in VirtualBox. Please note that XP Mode may not remain activated after importing it into VirtualBox. When you activate it, use the key that is located at C:\Program Files\Windows XP Mode\key.txt. Note: During our tests we weren’t able to get the activation to go through. We are looking into the issue and will have a revised article showing the correct way to get XP Mode in VirutalBox working correctly soon. Now we have one final thing to install – the VirtualBox Guest Additions. In the VirtualBox window, click “Devices” and then select “Install Guest Additions”. This should automatically launch in XP; if it doesn’t, click Start, then My Computer, and finally double-click on the CD drive which should say VirtualBox Guest Additions. Simply install with the normal presets. You can select to install an experimental 3D graphics driver if you wish to try to run games in XP in VirtualBox; however, do note that this is not fully supported and is currently a test feature. You may see a prompt informing you that the drivers have not passed Logo testing; simply press “Continue Anyway” to proceed with the installation. When installation has completed, you will be required to reboot your virtual machine. Now, you can move your mouse directly from Windows XP to Windows 7 without pressing Ctrl. Integrating with Windows 7 Once your virtual machine is rebooted, you can integrate it with your Windows 7 desktop. In the VirtualBox window, click Machine and then select “Seamless Mode”. In Seamless mode you’ll have the XP Start menu and taskbar sit on top of your Windows 7 Start and Taskbar. Here we see XP running on Virtual Box in Seamless Mode. We have the old XP WordPad sitting next to the new Windows 7 version of WordPad. Another view of everything running seamlessly together on the same Windows 7 desktop. Hover the pointer over the XP taskbar to pull up the Virtual Box menu items. You can exit out of Seamless Mode from the VirtualBox menu or using “Ctrl+L”. Then you go back to having it run separately on your desktop again. Conclusion Running XP Mode in a Virtual Machine is a great way to experience the feature on computers without Hardware Virtualization capabilities. If you prefer VMware Player, then you’ll want to check out our articles on how to run XP Mode on Windows 7 machines without Hardware Virtualization, and how to create an XP Mode for Windows 7 Home Premium and Vista. Download VirtualBox Download XP Mode Similar Articles Productive Geek Tips Install XP Mode with VirtualBox Using the VMLite PluginUsing Windows 7 or Vista Compatibility ModeMake Safari Stop Crashing Every 20 Seconds on Windows VistaForce Windows 7 / Vista to Boot Into Safe Mode Without Using the F8 KeyHow To Run Chrome OS in VirtualBox TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Enable Check Box Selection in Windows 7 OnlineOCR – Free OCR Service Betting on the Blind Side, a Vanity Fair article 30 Minimal Logo Designs that Say More with Less LEGO Digital Designer – Free Create a Personal Website Quickly using Flavors.me

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How To Run XP Mode in VirtualBox on Windows 7 (sort of)

- by Matthew Guay

A few weeks ago we showed you how to run XP Mode on a Windows 7 computer without Hardware Virtualization using VMware. Some of you have been asking if it can be done in Virtual Box as well. The answer is “Yes!” and here we’ll show you how. Editor Update: Apparently there isn’t a way to activate XP Mode through VirtualBox using this method. You will however, be able to run it for 30 days. We have a new updated article on how to Install XP Mode with VirtualBox Using the VMLite Plugin. Earlier we showed you how to run XP mode on windows 7 machines without hardware virtualization capability. Since then, a lot of you have been asking to a write up a tutorial about doing the same thing using VirtualBox. This makes it another great way to run XP Mode if your computer does not have hardware virtualization. Here we’ll see how to import the XP Mode from Windows 7 Professional, Enterprise, or Ultimate into VirtualBox so you can run XP in it for free. Note: You need to have Windows 7 Professional or above to use XP Mode in this manner. In our tests we were able to get it to run on Home Premium as well, but you’ll be breaking Windows 7 licensing agreements. Getting Started First, download and install XP Mode (link below). There is no need to download Virtual PC if your computer cannot run it, so just download the XP Mode from the link on the left. Install XP mode; just follow the default prompts as usual. Now, download and install VirtualBox 3.1.2 or higher(link below). Install as normal, and simply follow the default prompts. VirtualBox may notify you that your network connection will be reset during the installation. Press Yes to continue. During the install, you may see several popups asking you if you wish to install device drivers for USB and Network interfaces. Simply click install, as these are needed for VirtualBox to run correctly. Setup only took a couple minutes, and doesn’t require a reboot. Setup XP Mode in VirtualBox: First we need to copy the default XP Mode so VirtualBox will not affect the original copy. Browse to C:\Program Files\Windows XP Mode, and copy the file “Windows XP Mode base.vhd”. Paste it in another folder of your choice, such as your Documents folder. Once you’ve copied the file, right-click on it and click Properties. Uncheck the “Read-only” box in this dialog, and then click Ok. Now, in VirtualBox, click New to create a new virtual machine. Enter the name of your virtual machine, and make sure the operating system selected is Windows XP. Choose how much memory you want to allow the virtual machine to use. VirtualBox’ default is 192 Mb ram, but for better performance you can select 256 or 512Mb. Now, select the hard drive for the virtual machine. Select “Use existing hard disk”, then click the folder button to choose the XP Mode virtual drive. In this window, click Add, and then browse to find the copy of XP Mode you previously made. Make sure the correct virtual drive is selected, then press Select. After selecting the VHD your screen should look like the following then click Next. Verify the settings you made are correct. If not, you can go back and make any changes. When everything looks correct click Finish. Setup XP Mode Now, in VirtualBox, click start to run XP Mode. The Windows XP in this virtual drive is not fully setup yet, so you will have to go through the setup process. If you didn’t uncheck the “Read-only” box in the VHD properties before, you may see the following error. If you see it, go back and check the file to makes sure it is not read-only. When you click in the virtual machine, it will capture your mouse by default. Simply press the right Ctrl key to release your mouse so you can go back to using Windows 7. This will only be the case during the setup process; after the Guest Additions are installed, the mouse will seamlessly move between operating systems. Now, accept the license agreement in XP. Choose your correct locale and keyboard settings. Enter a name for your virtual XP, and an administrative password. Check the date, time, and time zone settings, and adjust them if they are incorrect. The time and date are usually correct, but the time zone often has to be corrected. XP will now automatically finish setting up your virtual machine, and then will automatically reboot. After rebooting, select your automatic update settings. You may see a prompt to check for drivers; simply press cancel, as all the drivers we need will be installed later with the Guest Additions. Your last settings will be finalized, and finally you will see your XP desktop in VirtualBox. Please note that XP Mode may not remain activated after importing it into VirtualBox. When you activate it, use the key that is located at C:\Program Files\Windows XP Mode\key.txt. Note: During our tests we weren’t able to get the activation to go through. We are looking into the issue and will have a revised article showing the correct way to get XP Mode in VirutalBox working correctly soon. Now we have one final thing to install – the VirtualBox Guest Additions. In the VirtualBox window, click “Devices” and then select “Install Guest Additions”. This should automatically launch in XP; if it doesn’t, click Start, then My Computer, and finally double-click on the CD drive which should say VirtualBox Guest Additions. Simply install with the normal presets. You can select to install an experimental 3D graphics driver if you wish to try to run games in XP in VirtualBox; however, do note that this is not fully supported and is currently a test feature. You may see a prompt informing you that the drivers have not passed Logo testing; simply press “Continue Anyway” to proceed with the installation. When installation has completed, you will be required to reboot your virtual machine. Now, you can move your mouse directly from Windows XP to Windows 7 without pressing Ctrl. Integrating with Windows 7 Once your virtual machine is rebooted, you can integrate it with your Windows 7 desktop. In the VirtualBox window, click Machine and then select “Seamless Mode”. In Seamless mode you’ll have the XP Start menu and taskbar sit on top of your Windows 7 Start and Taskbar. Here we see XP running on Virtual Box in Seamless Mode. We have the old XP WordPad sitting next to the new Windows 7 version of WordPad. Another view of everything running seamlessly together on the same Windows 7 desktop. Hover the pointer over the XP taskbar to pull up the Virtual Box menu items. You can exit out of Seamless Mode from the VirtualBox menu or using “Ctrl+L”. Then you go back to having it run separately on your desktop again. Conclusion Running XP Mode in a Virtual Machine is a great way to experience the feature on computers without Hardware Virtualization capabilities. If you prefer VMware Player, then you’ll want to check out our articles on how to run XP Mode on Windows 7 machines without Hardware Virtualization, and how to create an XP Mode for Windows 7 Home Premium and Vista. Download VirtualBox Download XP Mode Similar Articles Productive Geek Tips Install XP Mode with VirtualBox Using the VMLite PluginUsing Windows 7 or Vista Compatibility ModeMake Safari Stop Crashing Every 20 Seconds on Windows VistaForce Windows 7 / Vista to Boot Into Safe Mode Without Using the F8 KeyHow To Run Chrome OS in VirtualBox TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Enable Check Box Selection in Windows 7 OnlineOCR – Free OCR Service Betting on the Blind Side, a Vanity Fair article 30 Minimal Logo Designs that Say More with Less LEGO Digital Designer – Free Create a Personal Website Quickly using Flavors.me

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SQL SERVER – Shrinking NDF and MDF Files – Readers’ Opinion

- by pinaldave

Previously, I had written a blog post about SQL SERVER – Shrinking NDF and MDF Files – A Safe Operation. After that, I have written the following blog post that talks about the advantage and disadvantage of Shrinking and why one should not be Shrinking a file SQL SERVER – SHRINKFILE and TRUNCATE Log File in SQL Server 2008. On this subject, SQL Server Expert Imran Mohammed left an excellent comment. I just feel that his comment is worth a big article itself. For everybody to read his wonderful explanation, I am posting this blog post here. Thanks Imran! Shrinking Database always creates performance degradation and increases fragmentation in the database. I suggest that you keep that in mind before you start reading the following comment. If you are going to say Shrinking Database is bad and evil, here I am saying it first and loud. Now, the comment of Imran is written while keeping in mind only the process showing how the Shrinking Database Operation works. Imran has already explained his understanding and requests further explanation. I have removed the Best Practices section from Imran’s comments, as there are a few corrections. Comments from Imran - Before I explain to you the concept of Shrink Database, let us understand the concept of Database Files. When we create a new database inside the SQL Server, it is typical that SQl Server creates two physical files in the Operating System: one with .MDF Extension, and another with .LDF Extension. .MDF is called as Primary Data File. .LDF is called as Transactional Log file. If you add one or more data files to a database, the physical file that will be created in the Operating System will have an extension of .NDF, which is called as Secondary Data File; whereas, when you add one or more log files to a database, the physical file that will be created in the Operating System will have the same extension as .LDF. The questions now are, “Why does a new data file have a different extension (.NDF)?”, “Why is it called as a secondary data file?” and, “Why is .MDF file called as a primary data file?” Answers: Note: The following explanation is based on my limited knowledge of SQL Server, so experts please do comment. A data file with a .MDF extension is called a Primary Data File, and the reason behind it is that it contains Database Catalogs. Catalogs mean Meta Data. Meta Data is “Data about Data”. An example for Meta Data includes system objects that store information about other objects, except the data stored by the users. sysobjects stores information about all objects in that database. sysindexes stores information about all indexes and rows of every table in that database. syscolumns stores information about all columns that each table has in that database. sysusers stores how many users that database has. Although Meta Data stores information about other objects, it is not the transactional data that a user enters; rather, it’s a system data about the data. Because Primary Data File (.MDF) contains important information about the database, it is treated as a special file. It is given the name Primary Data file because it contains the Database Catalogs. This file is present in the Primary File Group. You can always create additional objects (Tables, indexes etc.) in the Primary data file (This file is present in the Primary File group), by mentioning that you want to create this object under the Primary File Group. Any additional data file that you add to the database will have only transactional data but no Meta Data, so that’s why it is called as the Secondary Data File. It is given the extension name .NDF so that the user can easily identify whether a specific data file is a Primary Data File or a Secondary Data File(s). There are many advantages of storing data in different files that are under different file groups. You can put your read only in the tables in one file (file group) and read-write tables in another file (file group) and take a backup of only the file group that has read the write data, so that you can avoid taking the backup of a read-only data that cannot be altered. Creating additional files in different physical hard disks also improves I/O performance. A real-time scenario where we use Files could be this one: Let’s say you have created a database called MYDB in the D-Drive which has a 50 GB space. You also have 1 Database File (.MDF) and 1 Log File on D-Drive and suppose that all of that 50 GB space has been used up and you do not have any free space left but you still want to add an additional space to the database. One easy option would be to add one more physical hard disk to the server, add new data file to MYDB database and create this new data file in a new hard disk then move some of the objects from one file to another, and put the file group under which you added new file as default File group, so that any new object that is created gets into the new files, unless specified. Now that we got a basic idea of what data files are, what type of data they store and why they are named the way they are, let’s move on to the next topic, Shrinking. First of all, I disagree with the Microsoft terminology for naming this feature as “Shrinking”. Shrinking, in regular terms, means to reduce the size of a file by means of compressing it. BUT in SQL Server, Shrinking DOES NOT mean compressing. Shrinking in SQL Server means to remove an empty space from database files and release the empty space either to the Operating System or to SQL Server. Let’s examine this through an example. Let’s say you have a database “MYDB” with a size of 50 GB that has a free space of about 20 GB, which means 30GB in the database is filled with data and the 20 GB of space is free in the database because it is not currently utilized by the SQL Server (Database); it is reserved and not yet in use. If you choose to shrink the database and to release an empty space to Operating System, and MIND YOU, you can only shrink the database size to 30 GB (in our example). You cannot shrink the database to a size less than what is filled with data. So, if you have a database that is full and has no empty space in the data file and log file (you don’t have an extra disk space to set Auto growth option ON), YOU CANNOT issue the SHRINK Database/File command, because of two reasons: There is no empty space to be released because the Shrink command does not compress the database; it only removes the empty space from the database files and there is no empty space. Remember, the Shrink command is a logged operation. When we perform the Shrink operation, this information is logged in the log file. If there is no empty space in the log file, SQL Server cannot write to the log file and you cannot shrink a database. Now answering your questions: (1) Q: What are the USEDPAGES & ESTIMATEDPAGES that appear on the Results Pane after using the DBCC SHRINKDATABASE (NorthWind, 10) ? A: According to Books Online (For SQL Server 2000): UsedPages: the number of 8-KB pages currently used by the file. EstimatedPages: the number of 8-KB pages that SQL Server estimates the file could be shrunk down to. Important Note: Before asking any question, make sure you go through Books Online or search on the Google once. The reasons for doing so have many advantages: 1. If someone else already has had this question before, chances that it is already answered are more than 50 %. 2. This reduces your waiting time for the answer. (2) Q: What is the difference between Shrinking the Database using DBCC command like the one above & shrinking it from the Enterprise Manager Console by Right-Clicking the database, going to TASKS & then selecting SHRINK Option, on a SQL Server 2000 environment? A: As far as my knowledge goes, there is no difference, both will work the same way, one advantage of using this command from query analyzer is, your console won’t be freezed. You can do perform your regular activities using Enterprise Manager. (3) Q: What is this .NDF file that is discussed above? I have never heard of it. What is it used for? Is it used by end-users, DBAs or the SERVER/SYSTEM itself? A: .NDF File is a secondary data file. You never heard of it because when database is created, SQL Server creates database by default with only 1 data file (.MDF) and 1 log file (.LDF) or however your model database has been setup, because a model database is a template used every time you create a new database using the CREATE DATABASE Command. Unless you have added an extra data file, you will not see it. This file is used by the SQL Server to store data which are saved by the users. Hope this information helps. I would like to as the experts to please comment if what I understand is not what the Microsoft guys meant. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Readers Contribution, Readers Question, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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