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  • StackOverflow Error at java.util.AbstractColllection.<init>(Unknown Source)

    - by thebulge
    I fixed my prior problem yesterday by just separating all the classes into separate files. Nevertheless, I wrote all the code down and seeing no errors was able to compile the program. Or so I thought. Here's the error code: Exception in thread "main" java.lang.StackOverflowError at java.util.AbstractCollection.<init>(Unknown Source) at java.util.AbstractList.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source Here are the spots where my I get the errors(marked with problem?) public class GameWorld implements IObservable, IGameWorld { // create collections class public Vector<GameObject> GameObjectList = new Vector<GameObject>(); // PROBLEM private Vector<IObserver> ObserverList = new Vector<IObserver>(); // declare objects Tank pTank = new Tank(10, 10); // other objects and variables to declare public GameWorld() { // add objects to GameObjectList } // accessors/mutators } I get another error here public class Tank extends Movable implements ISteerable { private int armorStrength; private int missileCount; public Tank() {} public Tank(int armStr, int misslCt) // problem? { armorStrength = armStr; // default armorStrength missileCount = misslCt; // default missileCount } public void setDirection(int direction) { this.setDirection(direction); // get input from left turn or right turn // updateValues(); } // access/mutators here I'm stumped on what to do here.

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  • Make a PHP GET request from a PHP script and exit

    - by Abs
    Hello all, Is there something simpler than the following. I am trying to make a GET request to a PHP script and then exit the current script. I think this is a job for CURL but is there something simpler as I don't want to really worry about enabling the CURL php extension? In addition, will the below start the PHP script and then just come back and not wait for it to finish? //set GET variables $url = 'http://domain.com/get-post.php'; $fields = array( 'lname'=>urlencode($last_name), 'fname'=>urlencode($first_name) ); //url-ify the data for the GET foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; } rtrim($fields_string,'&'); //open connection $ch = curl_init(); //set the url, number of POST vars, POST data curl_setopt($ch,CURLOPT_URL,$url); curl_setopt($ch,CURLOPT_GET,count($fields)); curl_setopt($ch,CURLOPT_GETFIELDS,$fields_string); //execute GET $result = curl_exec($ch); //close connection curl_close($ch); I want to run the other script which contains functions when a condition is met so a simple include won't work as the if condition wraps around the functions, right? Please note, I am on windows machine and the code I am writing will only be used on a Windows OS. Thanks all for any help and advice

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  • how to filter text of the selected value in drop down

    - by Carlos
    I have a drop down menu. Has product types. Product types have associated value (from drop down) values correspond to machine groups. So each option should have three variables--Machine name, values, machine group. I can get the Machine name and I can get the machine value (and display them in a different field)...what I have not been able to figure out is how to change the value into the Machine group. jQuery('#MachineName').bind('change', function() { //get selected value from drop down; var selectedValue = jQuery("#MachineName").val(); //populate a text field with the selected drop down value jQuery("#MachineValue").val(selectedValue); What I would like to do is keep that MachineValue but then populate another text field with the sorted MachineGroup I have been trying to run it through something like switch(jQuery(this).val()){ case "236" : newVal = "8"; break; But I don't want to "change" the value I just want to do an "if then" type filter, so maybe something like: '236' => "8", '237' => "5", I just don't know how to properly say "assign the MachineGroup based on the MachineValue" (and then have it populate a different text field) In the end I would have three fields. The drop down, the MachineValue and the MachineGroup. Drop down and value are done, I just need to do Group. (And I can sort Group based on MachineName...just not sure which would be easier)

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  • problem using fprintf

    - by shiran bar
    I'm trying to print to a text file numerous variables yet it doesn't work. I checked and verified that i write it in the correct syntax. I also checked the return value and it's positive therefore i know it did write to the file, however when i open the file it's empty. I would be happy for some help. This is the code: I initiate DynsaleDayPtr in the main: FILE* DynsaleDayPtr = CreateTextFiles("sale_day.txt"); Create function: FILE* CreateTextFiles (char* fileName) { FILE* saleFilePtr=NULL; if((saleFilePtr=fopen(fileName,"a+"))==NULL) printf("File couldn't be opened\n"); return saleFilePtr; } The call to the function TextAddSale is done from a function that is called in the main: TextAddSale(DynSaleDayPtr,dynNumOfRecords); Bool TextAddSale (FILE* DynsaleDayPtr, int* dynNumOfRecords) { char id[6]; char name [50]; char priceChar[20]; char* tmp = NULL; int price=-1; DynamicRecord * newRec=NULL; scanf("%s%s%s",id,name,priceChar); newRec = (DynamicRecord *)malloc(sizeof(DynamicRecord)); if (newRec == NULL) return False; tmp = (char*)malloc(strlen(name)+1); if (tmp == NULL) { free (newRec); return False; } strcpy(tmp,name); newRec->productName = tmp; strcpy(newRec->productId, id); newRec->productPrice=atoi (priceChar); if (fprintf(DynsaleDayPtr,"%d %s %s %d", strlen(newRec->productName), newRec->productId, newRec->productName, newRec->productPrice)>0) { *dynNumOfRecords=(*dynNumOfRecords)+1; return True; } } thanks!

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  • Inheritance not working

    - by Pendo826
    Hey im just practicing inheritance and i encountered a problem. Im getting an error in my car class(sub-class) that the variables in Vehicle(parent) are not visible. i didnt do anything to change this and i dont even know how to make it invisible. Can anyone help me with this. public class Vehicle { private String make, model, colour; private int registrationNumber; public Vehicle() { this.make = ""; this.model = ""; this.colour = ""; this.registrationNumber = 0; } public Vehicle(String make, String model, String colour, int registrationNumber) { this.make = make; this.model = model; this.colour = colour; this.registrationNumber = registrationNumber; } public String getMake() { return make; } public void setMake(String make) { this.make = make; } public String getModel() { return model; } public void setModel(String model) { this.model = model; } public String getColour() { return colour; } public void setColour(String colour) { this.colour = colour; } public int getRegistrationNumber() { return registrationNumber; } public void setRegistrationNumber(int registrationNumber) { this.registrationNumber = registrationNumber; } public String toString() { return "Vehicle [make=" + make + ", model=" + model + ", colour=" + colour + ", registrationNumber=" + registrationNumber + "]"; } } public Car() { super(); this.doors = 0; this.shape = ""; } public Car(int doors, String shape, String make, String model, String colour, int registrationNumber) { super(); this.doors = doors; this.shape = shape; this.make = make;//Error this.model = model;//Error this.colour = colour;//Error this.registrationNumber = registrationNumber;//Error } The error message: Description Resource Path Location Type The field Vehicle.make is not visible Car.java /VehicleApp/src line 19 Java Problem The field Vehicle.model is not visible Car.java /VehicleApp/src line 20 Java Problem The field Vehicle.colour is not visible Car.java /VehicleApp/src line 21 Java Problem The field Vehicle.registrationNumber is not visible Car.java /VehicleApp/src line 22 Java Problem

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  • Parse particular text from an XML string

    - by Dan Sewell
    Hi all, Im writing an app which reads an RSS feed and places items on a map. I need to read the lat and long numbers only from this string: http://www.xxxxxxxxxxxxxx.co.uk/map.aspx?isTrafficAlert=true&lat=53.647351&lon=-1.933506 .This is contained in link tags Im a bit of a programming noob but im writing this in C#/Silverlight using Linq to XML. Shold this text be extrated when parsing or after parsing and sent to a class to do this? Many thanks for your assistance. EDIT. Im going to try and do a regex on this this is where I need to integrate the regex somewhere in this code. I need to take the lat and long from the Link element and seperate it into two variables I can use (the results are part of a foreach loop that creates a list.) var events = from ev in document.Descendants("item") select new { Title = (ev.Element("title").Value), Description = (ev.Element("description").Value), Link = (ev.Element("link").Value), }; Question is im not quite ure where to put the regex (once I work out how to use the regex properly! :-) )

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  • How do I display core data on second view controller?

    - by jon
    I am working on my first core data iPhone application. I am using a navigation controller, and the root view controller displays 4 rows. Clicking the first row takes me to a second table view controller. However, when I click the back button, repeat the row tap, click the back button again, and tap the row a third time, I get an error. I have been researching this for a week with no success. I can reproduce the error easily: Create a new Navigation-based Application, use Core Data for storage, call it MyTest which creates MyTestAppDelegate and RootViewController. Add new UIViewController subclass, with UITableViewController and xib, call it ListViewController. Copy code from RootViewController.h and .m to ListViewController.h and .m., changing the file names appropriately. To simplify the code, I removed the trailing “_” from all variables. In RootViewController, I added #import ListViewController.h, set up an array to display 4 rows and navigate to ListViewController when clicking the first row. In ListViewController.m, I added #import MyTestAppDelegate.h” and the following code: - (void)viewDidLoad { [super viewDidLoad]; if (managedObjectContext == nil) { managedObjectContext = [(MyTestAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext]; } .. } The sequence that causes the error is tap row, return, tap row, return, tap row - error. managedObjectContext is synthesized for the third time. I appreciate your patience and your help, as this makes no sense to me. ADDENDUM: I may have a partial solution. http://www.iphonedevsdk.com/forum/iphone-sdk-development/41688-accessing-app-delegates-managed-object-context.html If I do not release the managedObjectContext in the .m file, the error goes away. Is that ok or will that cause me issues? - (void)dealloc { [fetchedResultsController release]; // [managedObjectContext release]; [super dealloc]; } ADDENDUM 2: See solution below. Sorry for the formatting issues - this was my first post.

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  • In C# should I reuse a function / property parameter to compute cleaner temporary value or create a

    - by Hamish Grubijan
    The example below may not be problematic as is, but it should be enough to illustrate a point. Imagine that there is a lot more work than trimming going on. public string Thingy { set { // I guess we can throw a null reference exception here on null. value = value.Trim(); // Well, imagine that there is so much processing to do this.thingy = value; // That this.thingy = value.Trim() would not fit on one line ... So, if the assignment has to take two lines, then I either have to abusereuse the parameter, or create a temporary variable. I am not a big fan of temporary variables. On the other hand, I am not a fan of convoluted code. I did not include an example where a function is involved, but I am sure you can imagine it. One concern I have is if a function accepted a string and the parameter was "abused", and then someone changed the signature to ref in both places - this ought to mess things up, but ... who would knowingly make such a change if it already worked without a ref? Seems like it is their responsibility in this case. If I mess with the value of value, am I doing something non-trivial under the hood? If you think that both approaches are acceptable, then which do you prefer and why? Thanks.

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  • excel:mysql: rs.Update not working

    - by every_answer_gets_a_point
    i am updating a table using an ODBC connection from excel to mysql unfortunately the only column that gets updated is this one: .Fields("instrument") = "NA" where i am assigning variables to .Fields, it is putting NULL values!! what is going on here? here's the code Option Explicit Dim oConn As ADODB.Connection Private Sub ConnectDB() Set oConn = New ADODB.Connection oConn.Open "DRIVER={MySQL ODBC 5.1 Driver};" & _ "SERVER=localhost;" & _ "DATABASE=employees;" & _ "USER=root;" & _ "PASSWORD=pas;" & _ "Option=3" End Sub Function esc(txt As String) esc = Trim(Replace(txt, "'", "\'")) End Function Private Sub InsertData() Dim dpath, atime, rtime, lcalib, aname, rname, bstate, instrument As String Dim rs As ADODB.Recordset Set rs = New ADODB.Recordset ConnectDB With wsBooks rs.Open "batchinfo", oConn, adOpenKeyset, adLockOptimistic, adCmdTable Worksheets.Item("Report 1").Select dpath = Trim(Range("B2").Text) atime = Trim(Range("B3").Text) rtime = Trim(Range("B4").Text) lcalib = Trim(Range("B5").Text) aname = Trim(Range("B6").Text) rname = Trim(Range("B7").Text) bstate = Trim(Range("B8").Text) ' instrument = GetInstrFromXML(wbBook.FullName) With rs .AddNew ' create a new record ' add values to each field in the record .Fields("datapath") = dpath .Fields("analysistime") = atime .Fields("reporttime") = rtime .Fields("lastcalib") = lcalib .Fields("analystname") = aname .Fields("reportname") = rname .Fields("batchstate") = bstate .Fields("instrument") = "NA" .Update ' stores the new record End With ' get the last id Set rs = oConn.Execute("SELECT @@identity", , adCmdText) 'MsgBox capture_id rs.Close Set rs = Nothing End With End Sub

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  • JSON element detection

    - by user3614570
    I’ve created a string… {"atts": [{"name": "wedw"}, {"type": "---"}]} I pile a bunch of these together in an array based on user input and attach them to another string to complete a JSON object that tests out as valid. So I end up with a global array called fields with a bunch of these little snippets. So how do I change the name "weds" with a new name? I’ve tried... function changefieldname(pos){ var obj = JSON.parse(jsonstring); var oldname = obj.tracelog.fields[pos].atts[0]["name"]; var newname = document.getElementById("newlogfieldname"+pos).value; fields[pos].replace(oldname, newname); //writejson(); } And a bunch of variations. I know everything is checking out correct interms of the variables pos, oldname, and newname. I also know that fields[pos] returns the string in the array I want to correct but it’s not happy. I also tried converting fields[pos] to a string, but the replace function doesn't work on it. I’m sure there is a good reason.

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  • [C]Dynamic allocation memory of structure, related to GTK

    - by MakeItWork
    Hello, I have following structure: typedef struct { GtkWidget* PoziomaLinijka; GtkWidget* PionowaLinijka; GtkWidget* Label1; GtkWidget* Label2; gint x,y; } StrukturaDrawing; And i need to allocate it on the heap because later I have functions which uses that structure and I don't want to use global variables. So I allocate it like this: StrukturaDrawing* Wsk; Wsk = (StrukturaDrawing*)malloc(sizeof(StrukturaDrawing)); if (!Wsk) { printf("Error\n"); } And it doesn't returning error and also works great with other functions, it works the way I wanted it to work so finally i wanted to free that memory and here is problem because in Debug Mode compilator bitches: First-chance exception at 0x102d12b4 in GTK.exe: 0xC0000005: Access violation reading location 0xfffffffc. Unhandled exception at 0x102d12b4 in GTK.exe: 0xC0000005: Access violation reading location 0xfffffffc. I connect callback to my function, like that: g_signal_connect(G_OBJECT(Okno), "destroy", G_CALLBACK(Wyjscie), Wsk); Function which is suppose to free memory and close program: void Wyjscie(GtkWindow* window, GdkEvent* event, StrukturaDrawing* data) { gtk_main_quit(); free(data); data = NULL; } Any help really appreciated.

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  • XSLT; parse escaped text to a node-set and extract subelements

    - by Tom W
    Hello SO; I've been fighting with this problem all day and am just about at my wit's end. I have an XML file in which certain portions of data are stored as escaped text but are themselves well-formed XML. I want to convert the whole hierarchy in this text node to a node-set and extract the data therein. No combination of variables and functions I can think of works. The way I'd expect it to work would be: <xsl:variable name="a" select="InnerXML"> <xsl:for-each select="exsl:node-set($a)/*"> 'do something </xsl:for-each> The input element InnerXML contains text of the form <root><element a>text</element a><element b><element c/><element d>text</element d></element b></root> but that doesn't really matter. I just want to navigate the xml like a normal node-set. Where am I going wrong?

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  • C++: Conceptual problem in designing an intepreter

    - by sub
    I'm programming an interpreter for an experimental programming language (educational, fun,...) So far, everything went well (Tokenizer & Parser), but I'm getting a huge problem with some of the data structures in the part that actually runs the tokenized and parsed code. My programming language basically has only two types, int and string, and they are represented as C++ strings (std class) and ints Here is a short version of the data structure that I use to pass values around: enum DataType { Null, Int, String } class Symbol { public: string identifier; DataType type; string stringValue; int intValue; } I can't use union because string doesn't allow me to. This structure above is beginning to give me a headache. I have to scatter code like this everywhere in order to make it work, it is beginning to grow unmaintainable: if( mySymbol.type == Int ) { mySymbol.intValue = 1234; } else { mySymbol.stringValue = "abcde"; } I use the Symbol data structure for variables, return values for functions and general representation of values in the programming language. Is there any better way to solve this? I hope so!

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  • curl run out very slowly.

    - by sabuj
    here is my code bellow: $url = "http://localhost/Test/post_output.php"; $post_data = array ( "foo" => "bar", "query" => "Nettuts", "action" => "Submit" ); $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // we are doing a POST request curl_setopt($ch, CURLOPT_POST, 1); // adding the post variables to the request curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data); curl_setopt($ch, CURLINFO_HEADER_OUT, true); curl_setopt($ch, CURLOPT_VERBOSE, true); // some output will go to stderr / error_log curl_setopt($ch, CURLOPT_TIMEOUT, 10); curl_setopt(CURLOPT_CONNECTTIMEOUT, 5); $output = curl_exec($ch); $errStr = curl_error($ch); $errNum = curl_errno($ch); $head = curl_getinfo($ch, CURLINFO_HEADER_OUT); $ci = curl_getinfo($ch); print_r(array($head, $errStr, $errNum, $ci)); exit; curl_close($ch); echo $output; This script outputs very slowly. Even outputs nothing... can anyone help out this. Thanks...

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  • Prolog Beginner: Trivial Example that I cannot get to work.

    - by sixtyfootersdude
    I have some prolog. The lessThanTen and example predicates work as expected however the exam predicate does not work. lessThanTen(9). lessThanTen(8). lessThanTen(7). lessThanTen(6). lessThanTen(5). lessThanTen(4). lessThanTen(3). lessThanTen(2). lessThanTen(1). lessThanTen(0). example(X) :- X is 5. exam(X) :- X is lessThanTen(Y). Here is the output: % swipl ... ?- [addv1]. Warning: /.../addv1.pl:17: Singleton variables: [Y] % addv1 compiled 0.00 sec, 1,484 bytes true. ?- lessThanTen(X). X = 9 ; X = 8 ; X = 7 ; ... ?- example(X). X = 5. ?- exam(X). ERROR: is/2: Arithmetic: `lessThanTen/1' is not a function ?- exam(5). ERROR: is/2: Arithmetic: `lessThanTen/1' is not a function I am thinking that the warning I am getting is pretty key.

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  • Error : 'java' is not recognized as an internal or external command, operable program or batch file.

    - by Setu
    I have my application online on the Google Apps Engine. When I deploy this application, this error is generated. I am using Netbeans 6.9. My jdk is installed at : "C:\Program Files\Java\jdk1.6.0_23\". I have installed Google App Engine for Java. This application is getting deployed & run on localhost very well. I am also able to start Google App Engine Server. I have set Environment variables as : 1) classpath : C:\Program Files\Java\jdk1.6.0_23\bin; 2) path : C:\Program Files\Java\jdk1.6.0_23\bin; 3) JAVA_HOME : C:\Program Files\Java\jdk1.6.0_23\bin; 4) include : C:\Program Files\Java\jdk1.6.0_23\include; 5) lib : C:\Program Files\Java\jdk1.6.0_23\lib; However, in system32, I am not finding java.exe, javac.exe or javawc.exe. Also, while running this : 1) java.exe 2) javac.exe 3) java -version from Command Line, they give proper output. How do I make my application properly deployed ?

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  • Why does this sql statement keep saying it is a boolean and not a parameter? (php/Mysql)

    - by ggfan
    In this statement, I am trying to see if there if the latest posting in the database that has the exact same title, price, city, state, detail. If there is, then it would say to the user that the exact post has been already made; if not then insert the posting into the dbc. (This is one type of check so that users can't accidentally post twice. This may not be the best check, but this statement error is annoying me, so I want it to work :)) Why won't this sql work? I think it's not letting the title=$title and not getting the value in the $title... ERROR: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in postad.php on line 365 //there is a form that users fill out that has title, price, city, etc <form> blah blah </form> //if users click submit, then does all the checks and if all okay, insert to dbc if (isset($_POST['submit'])) { // Grab the pposting data from the POST and gets rid of any funny stuff $title = mysqli_real_escape_string($dbc, trim($_POST['title'])); $price = mysqli_real_escape_string($dbc, trim($_POST['price'])); $city = mysqli_real_escape_string($dbc, trim($_POST['city'])); $state = mysqli_real_escape_string($dbc, trim($_POST['state'])); $detail = mysqli_real_escape_string($dbc, trim($_POST['detail'])); if (!is_numeric($price) && !empty($price)) { echo "<p class='error'>The price can only be numbers. No special characters, etc</p>"; } //Error problem...won't let me set title=$title, detail=$detail, etc. //this statement after all the checks so that none of the variables are empty $query="Select * FROM posting WHERE user_id={$_SESSION['user_id']} AND title=$title AND price=$price AND city=$city AND state=$state AND detail=$detail"; $data = mysqli_query($dbc, $query); if(mysqli_num_rows($data)==1) { echo "You already posted this ad. Most likely caused by refreshing too many times."; } }

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  • Create table class as a singleton

    - by Mark
    I got a class that I use as a table. This class got an array of 16 row classes. These row classes all have 6 double variables. The values of these rows are set once and never change. Would it be a good practice to make this table a singleton? The advantage is that it cost less memory, but the table will be called from multiple threads so I have to synchronize my code which way cause a bit slower application. However lookups in this table are probably a very small portion of the total code that is executed. EDIT: This is my code, are there better ways to do this or is this a good practice? Removed synchronized keyword according to recommendations in this question. final class HalfTimeTable { private HalfTimeRow[] table = new HalfTimeRow[16]; private static final HalfTimeTable instance = new HalfTimeTable(); private HalfTimeTable() { if (instance != null) { throw new IllegalStateException("Already instantiated"); } table[0] = new HalfTimeRow(4.0, 1.2599, 0.5050, 1.5, 1.7435, 0.1911); table[1] = new HalfTimeRow(8.0, 1.0000, 0.6514, 3.0, 1.3838, 0.4295); //etc } @Override @Deprecated public Object clone() throws CloneNotSupportedException { throw new CloneNotSupportedException(); } public static HalfTimeTable getInstance() { return instance; } public HalfTimeRow getRow(int rownumber) { return table[rownumber]; } }

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  • PHP: Trying to come up with a "prev" and "next" link

    - by fwaokda
    I'm displaying 10 records per page. The variables I have currently that I'm working with are.. $total = total number of records $page = whats the current page I'm displaying I placed this at the top of my page... if ( $_GET['page'] == '' ) { $page = 1; } //if no page is specified set it to `1` else { $page = ($_GET['page']); } // if page is specified set it Here are my two links... if ( $page != 1 ) { echo '<div style="float:left" ><a href="index.php?page='. ( $page - 1 ) .'" rev="prev" >Prev</a></div>'; } if ( !( ( $total / ( 10 * $page ) ) < $page ) ) { echo '<div style="float:right" ><a href="index.php?page='. ( $page + 1 ) .'" rev="next" >Next</a></div>'; } Now I guess (unless I'm not thinking of something) that I can display the "Prev" link every time except when the page is '1'. How can make it where the "Next" link doesn't show on the last page though?

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  • Dont understand the concept of extends in URL.openConnection() in JAVA

    - by user1722361
    Hi I am trying to learn JAVA deeply and so I am digging into the JDK source code in the following lines: URL url = new URL("http://www.google.com"); URLConnection tmpConn = url.openConnection(); I attached the source code and set the breakpoint at the second line and stepped into the code. I can see the code flow is: URL.openConnection() - sun.net.www.protocol.http.Handler.openConnection() I have two questions about this First In URL.openConnection() the code is: public URLConnection openConnection() throws java.io.IOException { return handler.openConnection(this); } handler is an object of URLStreamHandler, define as blow transient URLStreamHandler handler; But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right? But there are a lot classes who implement this methods in sun.net.www.protocol (like http.Hanlder, ftp.Handler ) How should the code know which "openConnection" method it should call? In this example, this handler.openConnection() will go into http.Handler and it is correct. (if I set the url as ftp://www.google.com, it will go into ftp.Handler) I cannot understand the mechanism. second. I have attached the source code so I can step into the JDK and see the variables but for many classes like sun.net.www.protocol.http.Handler, there are not source code in src.zip. I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip? Where can I find a comprehensive version of source code? Thanks!

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  • Questions about shifting from mysql to PDO

    - by Scarface
    Hey guys I have recently decided to switch all my current plain mysql queries performed with php mysql_query to PDO style queries to improve performance, portability and security. I just have some quick questions for any experts in this database interaction tool Will it prevent injection if all statements are prepared? (I noticed on php.net it wrote 'however, if other portions of the query are being built up with unescaped input, SQL injection is still possible' I was not exactly sure what this meant). Does this just mean that if all variables are run through a prepare function it is safe, and if some are directly inserted then it is not? Currently I have a connection at the top of my page and queries performed during the rest of the page. I took a look at PDO in more detail and noticed that there is a try and catch procedure for every query involving a connection and the closing of that connection. Is there a straightforward way to connecting and then reusing that connection without having to put everything in a try or constantly repeat the procedure by connecting, querying and closing? Can anyone briefly explain in layman's terms what purpose a set_exception_handler serves? I appreciate any advice from any more experienced individuals.

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  • php validate integer [updated]

    - by George Garchagudashvili
    Read B A: I'll give quick example: $a = "\n \t 34 3"; // string(9) $aint = intval($a); // int(34) var_dump($a == $aint); result: bool(true) call me noob but can you tell me why/how does these variables do pass equalization test? What I want to achieve is to check if '1989' equals 1989 would be true, but not any other case. ex: '1989 ' should not pass the test. Also I don't want to use regex. B: I need to validate if variable is integer, I've tried all the available built-in functions or helpful tips, but the only best solution would be regex which I don't want to use this time. also filter_var is not best because it also filters data, but I want to only validate it. 123 -123 '123' '-123' these inputs to be only true, false otherwise I've tried many different options: ctype_digit("-123"); // false - doesn't work is_int('123'); // false filter_var(' 123 ', FILTER_VALIDATE_INT) !== false; // true - doesn't work

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  • I need help with a SQL query. Fetching an entry, it's most recent revision and it's fields.

    - by Tigger ate my dad
    Hi there, I'm building a CMS for my own needs, and finished planning my database layout. Basically I am abstracting all possible data-models into "sections" and all entries into one table. The final layout is as follows: Database diagram: I have yet to be allowed to post images, so here is a link to a diagram of my database. Entries (section_entries) are children of their section (sections). I save all edits to the entries in a new revision (section_entries_revisions), and also track revisions on the sections (section_revisions), in order to match the values of a revision, to the fields of the section that existed when the entry-revision was made. The section-revisions can have a number of fields (section_revision_fields) that define the attributes of entries in the section. There is a many-to-many relationship between the fields (section_revision_fields) and the entry-revisions (section_entry_revisions), that stores the values of the attributes defined by the section revision. Feel free to ask questions if the diagram is confusing. Now, this is the most complex SQL I've ever worked with, and the task of fetching my data is a little daunting. Basically what i want help with, is fetching an entry, when the only known variables are; section_id, section_entry_id. The query should fetch the most recent revision of that entry, and the section_revision model corresponding to section_revision_id in the section_entry_revisions table. It should also fetch the values of the fields in the section-revision. I was hoping for a query result, where there would be as many rows as fields in the section. Each row would contain the information of the entry and the section, and then information for one of the fields (e.g. each row corresponding to a field and it's value). I tried to explain the best I could. Again, feel free to ask questions if my description somehow lacking. I hope someone is up for the challenge. Best regards. :-)

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  • What's an effective way to reuse ArrayLists in a for loop?

    - by Patrick
    hi, I'm reusing the same ArrayList in a for loop, and I use for loop results = new ArrayList<Integer>(); experts = new ArrayList<Integer>(); output = new ArrayList<String>(); .... to create new ones. I guess this is wrong, because I'm allocating new memory. Is this correct ? If yes, how can I empty them ? Added: another example I'm creating new variables each time I call this method. Is this good practice ? I mean to create new precision, relevantFound.. etc ? Or should I declare them in my class, outside the method to not allocate more and more memory ? public static void computeMAP(ArrayList<Integer> results, ArrayList<Integer> experts) { //compute MAP double precision = 0; int relevantFound = 0; double sumprecision = 0; thanks

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  • Trouble understanding the semantics of volatile in Java

    - by HungryTux
    I've been reading up about the use of volatile variables in Java. I understand that they ensure instant visibility of their latest updates to all the threads running in the system on different cores/processors. However no atomicity of the operations that caused these updates is ensured. I see the following literature being used frequently A write to a volatile field happens-before every read of that same field . This is where I am a little confused. Here's a snippet of code which should help me better explain my query. volatile int x = 0; volatile int y = 0; Thread-0: | Thread-1: | if (x==1) { | if (y==1) { return false; | return false; } else { | } else { y=1; | x=1; return true; | return true; } | } Since x & y are both volatile, we have the following happens-before edges between the write of y in Thread-0 and read of y in Thread-1 between the write of x in Thread-1 and read of x in Thread-0 Does this imply that, at any point of time, only one of the threads can be in its 'else' block(since a write would happen before the read)? It may well be possible that Thread-0 starts, loads x, finds it value as 0 and right before it is about to write y in the else-block, there's a context switch to Thread-1 which loads y finds it value as 0 and thus enters the else-block too. Does volatile guard against such context switches (seems very unlikely)?

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