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• Most unintuitive behaviour in the .Net framework?

  - by BlueRaja

  Intended behavior is often another phrase for bug-which-we-knew-about-when-we-wrote-it, but-we-wrote-it-anyways. Because it was "intended" (or perhaps it is now too late or too difficult), many of these extremely-unintuitive bugs never get fixed. For instance, consider the following code (C#): TextInfo textInfo = Thread.CurrentThread.CurrentCulture.TextInfo; textInfo.ToTitleCase("hello world!"); //Returns "Hello World!" textInfo.ToTitleCase("hElLo WoRld!"); //Returns "Hello World!" textInfo.ToTitleCase("Hello World!"); //Returns "Hello World!" What would you expect textInfo.ToTitleCase("HELLO WORLD!"); to return? In fact, it returns "HELLO WORLD!". This was well-documented "intended behavior," but, in my eyes, is extremely unintuitive, and therefore a bug. What is some other unintuitive behavior like this in this in the .Net framework? Bonus points if you can provide a fix that does not break backwards-compatibility. Remember! Always keep these two simple rules in mind when designing an API (or anything else): Make the common case the default, and Keep It Simple, Stupid!

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• Static variable for communication among like-typed objects

  - by Dan Ray

  I have a method that asynchronously downloads images. If the images are related to an array of objects (a common use-case in the app I'm building), I want to cache them. The idea is, I pass in an index number (based on the indexPath.row of the table I'm making by way through), and I stash the image in a static NSMutableArray, keyed on the row of the table I'm dealing with. Thusly: @implementation ImageDownloader ... @synthesize cacheIndex; static NSMutableArray *imageCache; -(void)startDownloadWithImageView:(UIImageView *)imageView andImageURL:(NSURL *)url withCacheIndex:(NSInteger)index { self.theImageView = imageView; self.cacheIndex = index; NSLog(@"Called to download %@ for imageview %@", url, self.theImageView); if ([imageCache objectAtIndex:index]) { NSLog(@"We have this image cached--using that instead"); self.theImageView.image = [imageCache objectAtIndex:index]; return; } self.activeDownload = [NSMutableData data]; NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:[NSURLRequest requestWithURL:url] delegate:self]; self.imageConnection = conn; [conn release]; } //build up the incoming data in self.activeDownload with calls to didReceiveData... - (void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"Finished downloading."); UIImage *image = [[UIImage alloc] initWithData:self.activeDownload]; self.theImageView.image = image; NSLog(@"Caching %@ for %d", self.theImageView.image, self.cacheIndex); [imageCache insertObject:image atIndex:self.cacheIndex]; NSLog(@"Cache now has %d items", [imageCache count]); [image release]; } My index is getting through okay, I can see that by my NSLog output. But even after my insertObject: atIndex: call, [imageCache count] never leaves zero. This is my first foray into static variables, so I presume I'm doing something wrong. (The above code is heavily pruned to show only the main thing of what's going on, so bear that in mind as you look at it.)

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• Rails paginate array items one-by-one instead of page-by-page

  - by hnovick

  Hi Guys, I have a group of assets, let's call them "practitioners". I'm displaying these practitioners in the header of a calendar interface. There are 7 columns to the calendar. 7 columns = 7 practitioners per view/page. Right now: if the first page shows you practitioners 1-7, when you go the next page you will see practitioners 8-15, next page 16-23, etc. etc. i am wondering how to page the practitioners so that if the first page shows you practitioners 1-7, the next page will show you practitioners 2-8, then 3-9, etc. etc. i would greatly appreciate any help you can offer. here is the rails code i am working with. best regards, harris novick # get the default sort order sort_order = RESOURCE_SORT_ORDER # if we've been given asset ids, start our list with them unless params[:asset_ids].blank? params[:asset_ids] = params[:asset_ids].values unless params[:asset_ids].is_a?(Array) sort_order = "#{params[:asset_ids].collect{|id| "service_provider_resources.id = #{id} DESC"}.join(",")}, #{sort_order}" end @asset_set = @provider.active_resources(:include => {:active_services => :latest_approved_version}).paginate( :per_page => RESOURCES_IN_DAY_VIEW, :page => params[:page], :order => sort_order )

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• Excel VBA - export to UTF-8

  - by Tom

  The macro I created works fine, I just need to sort out the saving business. Now I get a popup asking me where to save it, but I would like it to save it under a default name and path AND encoded in UTF-8. This is my full code I use, the bottom part saves the document I presume. Public Sub ExportToTextFile(FName As String, Sep As String, SelectionOnly As Boolean, AppendData As Boolean) Dim WholeLine As String Dim fnum As Integer Dim RowNdx As Long Dim ColNdx As Integer Dim StartRow As Long Dim EndRow As Long Dim StartCol As Integer Dim EndCol As Integer Dim CellValue As String Dim teller As Integer 'Teller aangemaakt ter controle voor het aantal velden 'teller = 1 Application.ScreenUpdating = False On Error GoTo EndMacro: fnum = FreeFile If SelectionOnly = True Then With Selection StartRow = .Cells(1).Row StartCol = .Cells(26).Column EndRow = .Cells(.Cells.Count).Row EndCol = .Cells(.Cells.Count).Column End With Else With ActiveSheet.UsedRange StartRow = .Cells(1).Row StartCol = .Cells(26).Column EndRow = .Cells(.Cells.Count).Row EndCol = .Cells(26).Column End With End If If AppendData = True Then Open FName For Append Access Write As #fnum Else Open FName For Output Access Write As #fnum End If For RowNdx = StartRow To EndRow WholeLine = "" For ColNdx = StartCol To EndCol If Cells(RowNdx, ColNdx).Value = "" Then CellValue = "" Else CellValue = Cells(RowNdx, ColNdx).Value End If WholeLine = WholeLine & CellValue & Sep Next ColNdx WholeLine = Left(WholeLine, Len(WholeLine) - Len(Sep)) Print #fnum, WholeLine, "" 'Print #fnum, teller, WholeLine, "" 'teller = teller + 1 Next RowNdx EndMacro: On Error GoTo 0 Application.ScreenUpdating = True Close #fnum End Sub Sub Dump4Mini() Dim FileName As Variant Dim Sep As String FileName = Application.GetSaveAsFilename(InitialFileName:=Blank, filefilter:="Text (*.txt),*.txt") If FileName = False Then Exit Sub End If Sep = "|" If Sep = vbNullString Then Exit Sub End If Debug.Print "FileName: " & FileName, "Separator: " & Sep ExportToTextFile FName:=CStr(FileName), Sep:=CStr(Sep), SelectionOnly:=False, AppendData:=False End Sub

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• VBA: How go I get the total width from all controls in an MS-Access form?

  - by Stefan Åstrand

  Hi, This is probably very basic stuff, but please bear in mind I am completely new to these things. I am working on a procedure for my Access datasheet forms that will: Adjust the width of each column to fit content Sum the total width of all columns and subtract it from the size of the window's width Adjust the width of one of the columns to fit the remaining space This is the code that adjusts the width of each column to fit content (which works fine): Dim Ctrl As Control Dim Path As String Dim ClmWidth As Integer 'Adjust column width to fit content For Each Ctrl In Me.Controls If TypeOf Ctrl Is TextBox Then Path = Ctrl.Name Me(Path).ColumnWidth = -2 End If Next Ctrl How should I write the code so I get the total width of all columns? Thanks a lot! Stefan Solution This is the code that makes an Access datasheet go from this: To this: Sub AdjustColumnWidth(frm As Form, clm As String) On Error GoTo HandleError Dim intWindowWidth As Integer ' Window width property Dim ctrl As Control ' Control Dim intCtrlWidth As Integer ' Control width property Dim intCtrlSum As Integer ' Control width property sum Dim intCtrlAdj As Integer ' Control width property remaining after substracted intCtrSum 'Adjust column width to standard width For Each ctrl In frm.Controls If TypeOf ctrl Is TextBox Or TypeOf ctrl Is CheckBox Or TypeOf ctrl Is ComboBox Then Path = ctrl.Name frm(Path).ColumnWidth = 1500 End If Next ctrl 'Get total column width For Each ctrl In frm.Controls If TypeOf ctrl Is TextBox Or TypeOf ctrl Is CheckBox Or TypeOf ctrl Is ComboBox Then Path = ctrl.Name intCtrlWidth = frm(Path).ColumnWidth If Path <> clm Then intCtrlSum = intCtrlSum + intCtrlWidth End If End If Next ctrl 'Adjust column to fit window intWindowWidth = frm.WindowWidth - 270 intCtrlAdj = intWindowWidth - intCtrlSum frm.Width = intWindowWidth frm(clm).ColumnWidth = intCtrlAdj Debug.Print "Totalt (Ctrl): " & intCtrlSum Debug.Print "Totalt (Window): " & intWindowWidth Debug.Print "Totalt (Remaining): " & intCtrlAdj Debug.Print "clm : " & clm HandleError: GeneralErrorHandler Err.Number, Err.Description Exit Sub End Sub Code to call procedure: Private Sub Form_Load() Call AdjustColumnWidth(Me, "txtDescription") End Sub

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• How large a role does subjectiveness play in programming?

  - by Bob

  I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP. Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing. What role does subjectiveness play within the programming realm? Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting. The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance. But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought. It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work. Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?

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• URL "fragment identifier" semantics for HTML documents

  - by Pointy

  I've been working with a new installation of the "MoinMoin" wiki software. As I was playing with it, typing in mostly random test pages, I created a link with a fragment blah blah see also [[SomeStuff#whatever|some other stuff about whatever]] Then I needed to figure out how to create the anchor for that "whatever" fragment identifier. I don't recall having to do that with MediaWiki, so I had to dig around, but finally I found that MoinMoin has an "Anchor" macro: == Whatever == <<Anchor(whatever)>> Looking at the generated HTML, I was surprised to see an empty <span> tag with an "id" value of "whatever". I expected that it'd be an <a> tag with a "name" attribute of "whatever". I dug around and found the source, and there's a comment that says they changed it from an <a> tag in order to avoid some IE problem with <pre> sections. This confused me — not because of the IE thing, but because it looked to me as if their "fix" had left the whole anchor mechanism completely broken. Much to my surprise, however, further testing indicated that it worked fine. I wrote a test page with 300 <span> tags all with "id" values, and I further shocked myself when Firefox behaved exactly as I would have expected it to had I used <a> tags. It also worked when I changed all the <span> tags to <em>. So by this time, you're either as surprised as I was, or else you're thinking "how can somebody that dumb have so many reputation points?" If you're in the second category, is it really the case that I've been typing in HTML for about 15 years now — a lot of HTML — and it's somehow escaped my notice that browsers use the HTML fragment to find any sort of element with a matching "id"? mind status: blown

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• rewrite not a member of LiftRules

  - by José Leal

  Hi guys, I was following http://www.assembla.com/wiki/show/liftweb/URL_Rewriting tutorial for url rewritting in liftweb.. but I get this error: error: value rewrite is not a member of object net.liftweb.http.LiftRules .. it is really odd.. and the documentation says that it exists. I'm using idea IDE, and I've done everything from scratch, using the lift maven blank archifact. Some more info: [INFO] ------------------------------------------------------------------------ [INFO] Building Joseph3 [INFO] task-segment: [tomcat:run] [INFO] ------------------------------------------------------------------------ [INFO] Preparing tomcat:run [INFO] [resources:resources {execution: default-resources}] [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 0 resource [INFO] [yuicompressor:compress {execution: default}] [INFO] nb warnings: 0, nb errors: 0 [INFO] artifact org.mortbay.jetty:jetty: checking for updates from scala-tools.org [INFO] artifact org.mortbay.jetty:jetty: checking for updates from central [INFO] [compiler:compile {execution: default-compile}] [INFO] Nothing to compile - all classes are up to date [INFO] [scala:compile {execution: default}] [INFO] Checking for multiple versions of scala [INFO] /home/dpz/Scala/Doit/Joseph3/src/main/scala:-1: info: compiling [INFO] Compiling 2 source files to /home/dpz/Scala/Doit/Joseph3/target/classes at 1274922123910 [ERROR] /home/dpz/Scala/Doit/Joseph3/src/main/scala/bootstrap/liftweb/Boot.scala:16: error: value rewrite is not a member of object net.liftweb.http.LiftRules [INFO] LiftRules.rewrite.prepend(NamedPF("ProductExampleRewrite") { [INFO] ^ [ERROR] one error found [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] wrap: org.apache.commons.exec.ExecuteException: Process exited with an error: 1(Exit value: 1) [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 19 seconds [INFO] Finished at: Thu May 27 03:02:07 CEST 2010 [INFO] Final Memory: 20M/175M [INFO] ------------------------------------------------------------------------ Process finished with exit code 1 enter code here

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• How to use reflection to call a method and pass parameters whose types are unknown at compile time?

  - by MandoMando

  I'd like to call methods of a class dynamically with parameter values that are "parsed" from a string input. For example: I'd like to call the following program with these commands: c:myprog.exe MethodA System.Int32 777 c:myprog.exe MethodA System.float 23.17 c:myprog.exe MethodB System.Int32& 777 c:myprog.exe MethodC System.Int32 777 System.String ThisCanBeDone static void Main(string[] args) { ClassA aa = new ClassA(); System.Type[] types = new Type[args.Length / 2]; object[] ParamArray = new object[types.Length]; for (int i=0; i < types.Length; i++) { types[i] = System.Type.GetType(args[i*2 + 1]); // LINE_X: this will obviously cause runtime error invalid type/casting ParamArray[i] = args[i*2 + 2]; MethodInfo callInfo = aa.GetType().GetMethod(args[0],types); callInfo.Invoke(aa, ParamArray); } // In a non-changeable classlib: public class ClassA { public void MethodA(int i) { Console.Write(i.ToString()); } public void MethodA(float f) { Console.Write(f.ToString()); } public void MethodB(ref int i) { Console.Write(i.ToString()); i++; } public void MethodC(int i, string s) { Console.Write(s + i.ToString()); } public void MethodA(object o) { Console.Write("Argg! Type Trapped!"); } } "LINE_X" in the above code is the sticky part. For one, I have no idea how to assign value to a int or a ref int parameter even after I create it using Activator.CreatInstance or something else. The typeConverter does come to mind, but then that requires an explicit compile type casting as well. Am I looking at CLR with JavaScript glasses or there is way to do this?

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• MySQL Query That Can Pull the Data I am Seeking?

  - by Amy

  On the project I am working on, I am stuck with the table structure from Hades. Two things to keep in mind: I can't change the table structure right now. I'm stuck with it for the time being. The queries are dynamically generated and not hard coded. So, while I am asking for a query that can pull this data, what I am really working toward is an algorithm that will generate the query I need. Hopefully, I can explain the problem without making your eyes glaze over and your brain implode. We have an instance table that looks (simplified) along these lines: Instances InstanceID active 1 Y 2 Y 3 Y 4 N 5 Y 6 Y Then, there are multiple data tables along these lines: Table1 InstanceID field1 reference_field2 1 John 5 2 Sally NULL 3 Fred 6 4 Joe NULL Table2 InstanceID field3 5 1 6 1 Table3 InstanceID fieldID field4 5 1 Howard 5 2 James 6 2 Betty Please note that reference_field2 in Table1 contains a reference to another instance. Field3 in Table2 is a bit more complicated. It contains a fieldID for Table 3. What I need is a query that will get me a list as follows: InstanceID field1 field4 1 John Howard 2 Sally 3 Fred The problem is, in the query I currently have, I do not get Fred because there is no entry in Table3 for fieldID 1 and InstanceID 6. So, the very best list I have been able to get thus far is InstanceID field1 field4 1 John Howard 2 Sally In essence, if there is an entry in Table1 for Field 2, and there is not an entry in Table 3 that has the instanceID contained in field2 and the field ID contained in field3, I don't get the data from field1. I have looked at joins till I'm blue in the face, and I can't see a way to handle the case when table3 has no entry.

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• How would I structure the loop to go through inputs?

  - by dmanexe

  I am attempting to make a loop that will go through an array structured like this: $input[n][checked] $input[n][input] The 2nd input acts as a price multiplier, but doesn't have to exist (field can be blank). I don't think a foreach loop is right because I don't think it handles the inputs from the form in the correct dimensional array order to keep the information together. I have inputs on a form that look like this: <input type="checkbox" name="measure[<?php echo $item->id; ?>][checked]" value="<?php echo $item->id; ?>"> <input class="item_mult" type="text" name="measure[<?php echo $item->id; ?>][input]" /> I am attempting to make the loop go through and act as a multiplier on the input relative to its sibling field. (i.e. input[1][input] would be an integer that I want to retrieve later, grouped with input[1][checked]) <? $field = $this->input->post('measure',true); $totals = array(); foreach($field as $value): if ($value['input'] == TRUE) { $query = $this->db->get_where('items', array('id' => $value['input']))->row(); $totals[] = $query->price; ?> <p><?=$query->name?> - <?=money_format('%(#10n', $query->price)?></p> <?php } else { } endforeach; ?> And finally, the last code to array_sum and print the grand total: <? $grand_total = array_sum($totals); ?> <p><?=money_format('%(#10n', $grand_total)?></p> Eventually, I will need to store these records in a database, so I am sending complete item IDs through, etc.

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• How can I print a web page on a server?

  - by Gavin Schultz

  Suppose I develop a web page using the cool Google visualization API, and it does everything the user wants. They can the parameters, look at the graphs, and print the page to get a reasonable-looking report. All good. Now suppose I want to do the same thing server-side. For example, say we need a set of report generated at a specific time of day, printed to a PDF and emailed to a manager. It's not a user-initiated action, so we don't have a user's browser or their printer. We have a URL that would render the report if we had a browser, and that's it. Is there a good way to do this server-side? Is this just foolish? Has anyone done anything like that before? Do any of the major browsers have APIs that might provide such functionality? Keep in mind too that it's not just static HTML; probably javascript will be running first to shift the DOM around. I know we could implement a whole different reporting engine on the server side to do this, but that will (a) generate reports that look a bit different, and (b) require me to build/maintain two sets of functionality. Instead, I'd be happy if I could just render the page / pages I want in an invisible server-side browser and print it to a PDF (let's mostly ignore that step - I know any number of PDF printer drivers that could do this). I don't really want to do it ugly either - i.e. by starting a browser process and then sending keystrokes directly to the window either - that's just bound to fall apart with a slight nudge. The only related question I found had an answer like that. Any advice appreciated!

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• Set the selected item for a combobox in a datagrid

  - by JingJingTao

  I am using a datagrid which has many combobox fields in it, when I click the datagrid combobox the selected item or highlighted value is the last item in the list, but I would like it to highlight the first(top) item in the list. I know for just a combobox, all I need to do is change the combobox.selecteditem or combobox.selectedindex, but I'm not sure what to do in this case. I have binded the combobox to a table in the database and used a datatable to store the combobox values and then I add a row to the datatable, I think the reason the last item in the combobox is highlighted is because I added a row to the datatable. Thank you for your help. String strGetTypes = "SELECT holidaycodeVARCHAR4Pk, codedescVARCHAR45 FROM holidaytype ORDER BY holidaycodeVARCHAR4Pk Desc"; DataTable dtHolidayType = new DataTable(); MySqlDataAdapter dbaElements = new MySqlDataAdapter(strGetTypes, ShareSqlSettings.dbConnect); dbaElements.Fill(dtHolidayType); DataGridViewComboBoxCell cboxDays = new DataGridViewComboBoxCell(); cboxDays.DataSource = dtHolidayType; cboxDays.DisplayMember = "codedescVARCHAR45"; cboxDays.ValueMember = "holidaycodeVARCHAR4Pk"; //Blank row dtHolidayType.Rows.Add(1); // gridDailyEmp.Rows[j].Cells[day] = cboxDays;

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• TabControl winform c#

  - by Steve

  Hi, Does anyone know why my tabcontrol will not display on this form? Have a feeling it maybe something simple but at the moment i just get a blank form. Thanks using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace test_project_3 { public partial class TabTest : Form { public TabTest() { InitializeComponent(); WebBrowser WB = new WebBrowser(); WB.Navigate("www.google.com"); TabControl tc = new TabControl(); tc.Dock = DockStyle.Fill; tc.Show(); TabPage tp = new TabPage(); tp.Text = "test"; tp.Show(); tp.Controls.Add(WB); tc.TabPages.Add(tp); } } }

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• How to get current datetime on windows command line, in a suitable format for using in a filename?

  - by Rory

  What's a windows command line statement(s) I can use to get the current datetime in a format that I can put into a filename? I want to have a .bat file that zips up a directory into an archive with the current date & time as part of the name, eg "Code_2008-10-14_2257.zip". Is there any easy way I can do this, independent of the regional settings of the machine? I don't really mind about the date format, ideally it'd be yyyy-mm-dd but anything simple is fine. So far I've got this, which on my machine gives me "Tue_10_14_2008_230050_91" rem Get the datetime in a format that can go in a filename. set _my_datetime=%date%_%time% set _my_datetime=%_my_datetime: =_% set _my_datetime=%_my_datetime::=% set _my_datetime=%_my_datetime:/=_% set _my_datetime=%_my_datetime:.=_% rem now use the timestamp by in a new zip file name "d:\Program Files\7-Zip\7z.exe" a -r Code_%_my_datetime%.zip Code I can live with this but it seems a bit clunky. Ideally it'd be briefer and have the format mentioned earlier. I'm using Windows Server 2003 and Win XP Pro. I don't want to install additional utilities to achieve this (although I realise there are some that will do nice date formatting).

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• Uninitialized array offset

  - by kimmothy16

  Hey everyone, I am using PHP to create a form with an array of fields. Basically you can add an unlimited number of 'people' to the form and each person has a first name, last name, and phone number. The form requires that you add a phone number for the first person only. If you leave the phone number field blank on any others, the handler file is supposed to be programmed to use the phone number from the first person. So, my fields are: person[] - a hidden field with a value that is this person's primary key. fname[] - an input field lname[] - an input field phone[] - an input field My form handler looks like this: $people = $_POST['person'] $counter = 0; foreach($people as $person): if($phone[$counter] == '') { // use $phone[0]'s phone number } else { // use $phone[$counter] number } $counter = $counter + 1; endforeach; PHP doesn't like this though, it is throwing me an Notice: Uninitialized string offset error. I debugged it by running the is_array function on people, fname, lname, and phone and it returns true to being an array. I can also manually echo out $phone[2], etc. and get the correct value. I've also ran is_int on the $counter variable and it returned true, so I'm unsure why this isn't working as intended? Any help would be great!

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• What is optimal hardware configuration for heavy load LAMP application

  - by Piotr Kochanski

  I need to run Linux-Apache-PHP-MySQL application (Moodle e-learning platform) for a large number of concurrent users - I am aiming 5000 users. By concurrent I mean that 5000 people should be able to work with the application at the same time. "Work" means not only do database reads but writes as well. The application is not very typical, since it is doing a lot of inserts/updates on the database, so caching techniques are not helping to much. We are using InnoDB storage engine. In addition application is not written with performance in mind. For instance one Apache thread usually occupies about 30-50 MB of RAM. I would be greatful for information what hardware is needed to build scalable configuration that is able to handle this kind of load. We are using right now two HP DLG 380 with two 4 core processors which are able to handle much lower load (typically 300-500 concurrent users). Is it reasonable to invest in this kind of boxes and build cluster using them or is it better to go with some more high-end hardware? I am particularly curious how many and how powerful servers are needed (number of processors/cores, size of RAM) what network equipment should be used (what kind of switches, network cards) any other hardware, like particular disc storage solutions, etc, that are needed Another thing is how to put together everything, that is what is the most optimal architecture. Clustering with MySQL is rather hard (people are complaining about MySQL Cluster, even here on Stackoverflow).

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• Rails ActiveRecord::MultiparameterAssignmentErrors

  - by Neil Middleton

  I have the following code in my model: attr_accessor :expiry_date validates_presence_of :expiry_date, :on => :create, :message => "can't be blank" and the following in my view: <%= date_select :account, :expiry_date, :discard_day => true, :start_year => Time.now.year, :end_year => Time.now.year + 15, :order => [:month, :year] %> However, when I submit my form I get: ActiveRecord::MultiparameterAssignmentErrors in SignupController#create /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:3073:in `execute_callstack_for_multiparameter_attributes' /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:3028:in `assign_multiparameter_attributes' /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:2750:in `attributes=' /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:2438:in `initialize' Any ideas as to what the problem might be? I've looked at #93277 with no joy, so am kinda stuck. Adding day to the select does NOT resolve the issue. Any ideas?

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• Realizing program with decision tree logics

  - by Vytas999

  The system realizes a game “Think animal”. Main use case is: 1. System offers user to think about any animal and the system will try to guess it 2. The system starts asking questions from the start of decision tree. Ex., “Question: It has fur?”, and provides possible answers – yes or no. 3. If the user answers Yes, the system proceeds to these steps: a. System tries to guess animal that has that feature, ex. “My guess: Is it bear?” and provides with possible answers – yes or no. b. If the user answer is Yes, the system offers to think off another animal 4. If the user answers is No, the system moves to No node in decision tree and moves to 2 step (and starts from asking from new node). 5. If system runs out of nodes (i.e., empty yes or no node was reached): a. the system announces that it has given up, and ask user to enter: i. What animal he had in mind ii. What is his characteristic feature b. User enters requested data c. The system creates a new node and links it to yes or no of last active node. Where i can get some information and some examples, when implementing decision tree logics in MS SQL Server and C#..? Any information will be usefull. Thanks

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• Weird Qt SSL issue -- error "No Error" shows up, nothing else, and if I ignore it, everything works

  - by houbysoft

  The issue is as follows : in my Qt app, I have a QWebView, which I use to load a HTTPS page. Everything worked fine on my development machine, so I'm now trying to get it to run on a test machine. I ran the app, but the page didn't load (the QWebView was blank). After much debugging, I found the problem is that an SSL error shows up, and the sslErrors() signal is fired. Here is my sslErrors() handling code: void blah::sslErrors(QNetworkReply *reply, const QList<QSslError> &errors) { foreach(QSslError error, errors) { qDebug() << error.errorString() << endl; } reply->ignoreSslErrors(); } The only thing the above code prints is: "No error" So there's no error, but unless I call reply->ignoreSslErrors(), the page doesn't load (on the test machine, on my developer computer no error is reported). Huh? Is this a bug? Is it safe to ignore the error, if I make sure it's of the type "No error"?

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• XML: what processing rules apply for values intertwined with tags?

  - by iCE-9

  I've started working on a simple XML pull-parser, and as I've just defuzzed my mind on what's correct syntax in XML with regards to certain characters/sequences, ignorable whitespace and such (thank you, http://www.w3schools.com/xml/xml_elements.asp), I realized that I still don't know squat about what can be sketched up as the following case (which Validome finds well-formed very much; note that I only want to use xml files for data storage, no entities, DTD or Schemas needed): <bookstore> <book id="1"> <author>Kurt Vonnegut Jr.</author> <title>Slapstick</title> </book> We drop a pie here. <book id="2">Who cares anyway? <author>Stephen King</author> <title>The Green Mile</title> </book> And another one here. <book id="3"> <author>Next one</author> <title>This time with its own title</title> </book> </bookstore> "We drop a pie here." and "And another one here." are values of the 'bookstore' element. "Who cares anyway?" is a value related to the second 'book' element. How are these processed, if at all? Will "We drop a pie here." and "Another one here." be concatenated to form one value for the 'bookstore' element, or are they treated separately, stored somewhere, affecting the outcome of the parsing of the element they belong to, or...?

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• Correct initialization sequence for Linux serial port

  - by whitequark

  I wrote an application that must use serial ports on Linux, especially ttyUSB ones. Reading and writing operations are performed with standard select()/read() loop and write(), and there is probably nothing wrong in them, but initialization code (or absence of some part of it) damages something in the tty subsystem. Here it is: vuxboot(string filename, unsigned baud = B115200) : _debug(false) { _fd = open(filename.c_str(), O_RDWR | O_NOCTTY); if(!_fd) throw new io_error("cannot open port"); // Serial initialization was written with FTDI USB-to-serial converters // in mind. Anyway, who wants to use non-8n1 protocol? tcgetattr(_fd, &_termios); termios tio = {0}; tio.c_iflag = IGNPAR; tio.c_oflag = 0; tio.c_cflag = baud | CLOCAL | CREAD | CS8; tio.c_lflag = 0; tcflush(_fd, TCIFLUSH); tcsetattr(_fd, TCSANOW, &tio); } Another tcsetattr(_fd, TCSANOW, &_termios) sits in the destructor, but it is irrelevant. With or without this termios initialization, strange things happen in system after the application exits. Sometimes plain cat (or hd) exits immediately printing nothing or same stuff each time, sometimes it is waiting and not displaying any of the data that is surely sent onto the port; and close() (read() too, but not every time) emits a strange WARNING to dmesg referring to usb-serial.c. I checked the hardware and firmware tens of times (even on different machines) and I am sure it is working as intended; moreover, I stripped the firmware to just print same message over and over. How can I use serial port without destroying anything? Thanks.

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• Strings exported from a module have changed line breaks

  - by Jesse Millikan

  In a DrScheme project, I'm using a MrEd editor-canvas% with text% and inserting a string from a literal in a Scheme file. This results in an extra blank line in the editor for each line of text I'm trying to insert. I've tracked this down to the apparent fact that string literals from outside modules are getting extra line breaks. Here's a full example. The editor is irrelevant at this point, but it displays the result. ; test-literals.ss (module test-literals scheme (provide (all-defined-out)) (define exported-string "From another module with some more line breaks. ")) ; editor-test.ss (module editor-test scheme (require mred "test-literals.ss") (define w (instantiate frame% ("Editor Test" #f) )) (define c (instantiate editor-canvas% (w) (line-count 12) (min-width 400))) (define editor (instantiate text% ())) (send c set-editor editor) (send w show #t) (send editor erase) (send editor insert "Some text with some line breaks. ") (send editor insert exported-string)) And the result in the editor is Some text with some line breaks. From another module with some more line breaks. I've traced in and figured out that it's changing Unix line breaks to Windows line breaks when strings are imported from another module, but these display as double line breaks. Why is this happening and is there a way to stop it other than changing every imported string?

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• Making a query result equal to zero when a condition is null

  - by John

  Hello, I believe the query below should work. However, when I run it, the results are blank. I think this is happening since for now, the table "comment" is empty. So there is no instance where s.submissionid = c.submissionid. I would like to have the query below to work even if there if no s.submissionid that equals a c.submissionid. In this case, I would like countComments to equal zero. How can I do this? Thanks in advance, John $sqlStr = "SELECT s.loginid, s.submissionid s.title, s.url, s.displayurl, l.username, count(c.comment) AS countComments FROM submission AS s, login AS l, comment AS c, WHERE s.loginid = l.loginid AND s.submissionid = c.submissionid GROUP BY s.loginid, s.submissionid s.title, s.url, s.displayurl, l.username ORDER BY s.datesubmitted DESC LIMIT 10"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"samplesrec\">"; while ($row = mysql_fetch_array($result)) { echo '<tr>'; echo '<td class="sitename1"><a href="http://www.'.$row["url"].'">'.$row["title"].'</a></td>'; echo '</tr>'; echo '<tr>'; echo '<td class="sitename2"><a href="http://www...com/sandbox/members/index.php?profile='.$row["username"].'">'.$row["username"].'</a><a href="http://www...com/sandbox/comments/index.php?submission='.$row["title"].'">'.$row["countComments"].'</a></td>'; echo '</tr>'; } echo "</table>";

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• Link click does nothing after ajax switching?

  - by Neil

  An odd case I'm trying to figure out here. I'm trying to design a mailbox system, and making some of the options ajax-y. Here's the scenario: We have a page with 2 tabs, inbox and compose. Inbox is a essentially a list of links of the form mailbox.php?msg=xxx. Clicking on the inbox or compose tabs does an ajax switch. So, let's say we're on an message page: mailbox.php?msg=123 I click on "compose" - it ajax switches to a compose form. I change my mind, click on "inbox" - it goes back to a list of messages. Note, the url has not changed at this point (all has been done through ajax). I click on the same message as before. It should go back into that message. However, nothing happens! The url it should go to (mailbox.php?msg=123) IS the url showing in the address bar, but, due to the earlier ajax activity, it's showing the inbox. Thoughts on how to resolve this? And, out of curiosity, an explanation? Normally, clicking on a link that takes you to a page you're already on will reload the page. Thanks!

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