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  • Qt 101: Why can't I use this class?

    - by Airjoe
    I have experience with C++ but I've never really used Qt before. I'm trying to connect to a SQLite database, so I found a tutorial here and am going with that. In the QtCreator IDE, I went to Add New -- C++ Class and in the header file pasted in the header the header from that link and in the .cpp file I pasted the source. My main.cpp looks like this: #include <QtGui/QApplication> #include "mainwindow.h" #include "databasemanager.h" #include <qlabel.h> int main(int argc, char *argv[]) { QApplication a(argc, argv); MainWindow w; w.show(); DatabaseManager db(); QLabel hello("nothing..."); if(db.openDB()){ hello.setText("Win!"); } else{ hello.setText("Lame!"); } hello.resize(100, 30); hello.show(); return a.exec(); } And I'm getting this error: main.cpp:13: error: request for member 'openDB' in 'db', which is of non-class type 'DatabaseManager()' Can anyone point me in the right direction? I know "copypaste" code isn't good, I just wanted to see if I could get DB connectivity working and I figured something like this would be simple... thanks for the help.

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  • Why does it NOT give a segmentation violation?

    - by user198729
    The code below is said to give a segmentation violation: #include <stdio.h> #include <string.h> void function(char *str) { char buffer[16]; strcpy(buffer,str); } int main() { char large_string[256]; int i; for( i = 0; i < 255; i++) large_string[i] = 'A'; function(large_string); return 1; } It's compiled and run like this: gcc -Wall -Wextra hw.cpp && a.exe But there is nothing output. NOTE The above code indeed overwrites the ret address and so on if you really understand what's going underneath.

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  • Why my async call does not work?

    - by Petr
    Hi, I am trying to understand what is IAsyncresult good and therefore I wrote this code. The problem is it behaves as I called "MetodaAsync" normal way. While debugging, the program stops here until the method completed. Any help appreciated, thank you. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; namespace ConsoleApplication1 { class Program { delegate int Delegat(); static void Main(string[] args) { Program p=new Program(); Delegat d = new Delegat(p.MetodaAsync); IAsyncResult a = d.BeginInvoke(null, null); //I have removed callback int returned=d.EndInvoke(a); Console.WriteLine("AAA"); } private int MetodaAsync() { int AC=0; for (int I = 0; I < 600000; I++) { for (int A = 0; A < 6000000; A++) { } Console.Write("B"); } return AC; } } }

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  • Why doesn't this data binding work?

    - by Qwertie
    I have a ViewModel class that contains a list of points, and I am trying to bind it to a Polyline. The Polyline picks up the initial list of points, but does not notice when additional points are added even though I implement INotifyPropertyChanged. What's wrong? <StackPanel> <Button Click="Button_Click">Add!</Button> <Polyline x:Name="_line" Points="{Binding Pts}" Stroke="Black" StrokeThickness="5"/> </StackPanel> C# side: // code-behind _line.DataContext = new ViewModel(); private void Button_Click(object sender, RoutedEventArgs e) { // The problem is here: NOTHING HAPPENS ON-SCREEN! ((ViewModel)_line.DataContext).AddPoint(); } // ViewModel class public class ViewModel : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; public PointCollection Pts { get; set; } public ViewModel() { Pts = new PointCollection(); Pts.Add(new Point(1, 1)); Pts.Add(new Point(11, 11)); } public void AddPoint() { Pts.Add(new Point(25, 13)); if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("Pts")); } }

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  • Why wouldn't `new int[x]{}` be valid???

    - by dboarman-FissureStudios
    In MonoDevelop I have the following code which compiles: int[] row = new int[indices.Count]{}; However, at run-time, I get: Matrix.cs(53,53): Error CS0150: A constant value is expected (CS0150) (testMatrix) I know what this error means and forces me to then resize the array: int[] row = new int[indices.Count]{}; Array.Resize(ref row, rowWidth); Is this something I just have to deal with because I am using MonoDevelop on Linux? I was certain that under .Net 3.5 I was able to initialize an array with a variable containing the width of the array. Can anyone confirm that this is isolated? If so, I can report the bug to bugzilla.

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  • How to know why an animation stutters?

    - by Patrick Klug
    I have a few fairly simple animations (moving text around, moving ellipses etc.) and running in full screen (1920x1080 minus the task bar) the WPF Performance Suite reports a good framerate around 50 FPS throughout the animation. Dirty Rect Addition is somewhere around 300 rect/s, the SW frames are between 0 and 4 and the HW frames are between 3 and 5. Video memory usage is around 80 MB. Problem is that the animations stutters every other half second. My machine is a new Dell laptop XPS 15 with the GeForce GT 435 with 2GB memory. - The drivers are up to date. (The same behavior occurs on my netbook (in full screen) as well so I don't think it is hardware related.) If I make the window smaller the stutter goes away. The stutter occurs with the simplest of animations - even with just a couple of elements but adding more elements certainly makes it more noticeable. How can I find out what causes this stutter? When I think of it, I have not actually seen any WPF animations which run smoothly in full screen. Is this even possible?

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  • Why is log4j not behaving as expected?

    - by Kieveli
    I have a co-worker who is trying to get log4j to behave as follows: Log to Stdout By default, disable most output Show only messages from java.sql.PrepareStatement at level debug and up He's getting caught up in the 'level' vs 'priority'. Here is his config file: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE log4j:configuration SYSTEM "D:/Java/apache-log4j-1.2.15/src/main/resources/org/apache/log4j/xml/log4j.dtd" > <log4j:configuration> <!-- Appenders --> <appender name="stdout" class="org.apache.log4j.ConsoleAppender"> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%5p %d{ISO8601} [%t][%x] %c - %m%n" /> </layout> </appender> <!-- Loggers for ibatus and JDBC database --> <logger name="java.sql.PreparedStatement"> <level value="debug"/> </logger> <!-- The Root Logger --> <root> <level value="error"/> <appender-ref ref="stdout"/> </root> </log4j:configuration> The output from this shows no messages in the log output. How does he need to change his log4j.xml config file to make it behave as he's expecting?

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  • Why is my searchable activity's Intent.getAction() null?

    - by originalbryan
    I've followed the SearchManager documentation yet am still having trouble making one of my app's activities searchable. From my activity, the SearchDialog appears, I enter a query, hit search, my activity reopens, then I see this in the log: D/SearchDialog( 584): launching Intent { act=android.intent.action.SEARCH flg=0x10000000 cmp=com.clinkybot.geodroid2/.views.Waypoints (has extras) } I/SearchDialog( 584): Starting (as ourselves) #Intent;action=android.intent.action.SEARCH;launchFlags=0x10000000;component=com.clinkybot.geodroid2/.views.Waypoints;S.user_query=sdaf;S.query=sdaf;end I/ActivityManager( 584): Starting activity: Intent { act=android.intent.action.SEARCH flg=0x10000000 cmp=com.clinkybot.geodroid2/.views.Waypoints (has extras) } D/WAYPOINTS( 1018): NI Intent { cmp=com.clinkybot.geodroid2/.views.Waypoints (has extras) } D/WAYPOINTS( 1018): NI null D/WAYPOINTS( 1018): NI false It appears to me that everything is fine up until the last three lines. The "NI" lines are getIntent().toString(), getIntent().getAction(), and getIntent().hasExtra(SearchManager.QUERY) respectively. ActivityManager appears to be starting my activity with the correct action. Then when my activity starts, it contains no action!? What am I doing wrong? The relevant portion of my manifest is: <activity android:name=".views.Waypoints" android:label="Waypoints" android:launchMode="singleTop"> <intent-filter> <action android:name="android.intent.action.SEARCH" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> <meta-data android:name="android.app.searchable" android:resource="@xml/searchable" /> </activity>

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  • Why it's not "if" and not "else"?

    - by Roman
    I have this code: $link = mysql_connect("localhost", "ctmanager", "pswsafgcsadfgG"); if ( ! $link ) die("I cannot connect to MySQL.<br>\n"); else print "Connection is established.<br>\n"; print "a"; if ( mysql_create_db("ct", $link) ) print "AAA"; else print "BBB"; print "2"; die(); And this is the output: Connection is established. a So, I cannot understand how it's possible that neither "AAA" no "BBB" is outputted. Is it because program dies at mysql_create_db?

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  • Cocoa Touch: Why doesn't UINavigationController render 'Back' button?

    - by Joshua
    When I push a view controller it animates properly and slides in, the only problem is that no 'Back' button is rendered up top.The back button is still there, I can still tap it, it just doesn't render on the screen. This behavior is identical in both the simulator and on multiple devices. Is this a known issue or bug? Using 3.1.3 of the iPhone SDK. More information: It renders it for further levels, just not on the second level of nav controller. So Main Page (No back button - OK). Second level page (back button, but doesn't render - not OK). Third level page (Back button there and rendering - OK).

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  • Why is my UIViewController initializer never called?

    - by mystify
    I made a view-based project from a fresh template. There's a UIViewController which is created with an XIB. In the implementation I uncommented that and added an NSLog. But this is never called: // The designated initializer. Override to perform setup that is required before the view is loaded. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) { // Custom initialization NSLog(@"nib"); } return self; } since that is initialized from a nib / xib, that should be called for sure, right? however, it doesn't. I do get an NSLog message when I put that in viewDidLoad.

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  • Why are nanosleep() and usleep() too slow?

    - by user351990
    I have a program that generates packets to send to a receiver. I need an efficient method of introducing a small delay between the sending of each packet so as not to overrun the receiver. I've tried usleep() and nanosleep() but they seem to be too slow. I've implemented a busy wait loop and had more success, but it's not the most efficient method, I know. I'm interested in anyone's experiences in trying to do what I'm doing. Do others find usleep() and nanosleep() to function well for this type of application? Thanks, Danny Llewallyn

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  • Why isn't this file reading/writing program working?

    - by user320950
    This program is supposed to read files and write them. I took the file open checks out because they kept causing errors. The problem is that the files open like they are supposed to and the names are correct but nothing is on any of the text screens. Do you know what is wrong? #include<iostream> #include<fstream> #include<cstdlib> #include<iomanip> using namespace std; int main() { ifstream in_stream; // reads itemlist.txt ofstream out_stream1; // writes in items.txt ifstream in_stream2; // reads pricelist.txt ofstream out_stream3;// writes in plist.txt ifstream in_stream4;// read recipt.txt ofstream out_stream5;// write display.txt float price=' ',curr_total=0.0; int wrong=0; int itemnum=' '; char next; in_stream.open("ITEMLIST.txt", ios::in); // list of avaliable items out_stream1.open("listWititems.txt", ios::out); // list of avaliable items in_stream2.open("PRICELIST.txt", ios::in); out_stream3.open("listWitdollars.txt", ios::out); in_stream4.open("display.txt", ios::in); out_stream5.open("showitems.txt", ios::out); in_stream.close(); // closing files. out_stream1.close(); in_stream2.close(); out_stream3.close(); in_stream4.close(); out_stream5.close(); system("pause"); in_stream.setf(ios::fixed); while(in_stream.eof()) { in_stream >> itemnum; cin.clear(); cin >> next; } out_stream1.setf(ios::fixed); while (out_stream1.eof()) { out_stream1 << itemnum; cin.clear(); cin >> next; } in_stream2.setf(ios::fixed); in_stream2.setf(ios::showpoint); in_stream2.precision(2); while((price== (price*1.00)) && (itemnum == (itemnum*1))) { while (in_stream2 >> itemnum >> price) // gets itemnum and price { while (in_stream2.eof()) // reads file to end of file { in_stream2 >> itemnum; in_stream2 >> price; price++; curr_total= price++; in_stream2 >> curr_total; cin.clear(); // allows more reading cin >> next; } } } out_stream3.setf(ios::fixed); out_stream3.setf(ios::showpoint); out_stream3.precision(2); while((price== (price*1.00)) && (itemnum == (itemnum*1))) { while (out_stream3 << itemnum << price) { while (out_stream3.eof()) // reads file to end of file { out_stream3 << itemnum; out_stream3 << price; price++; curr_total= price++; out_stream3 << curr_total; cin.clear(); // allows more reading cin >> next; } return itemnum, price; } } in_stream4.setf(ios::fixed); in_stream4.setf(ios::showpoint); in_stream4.precision(2); while ( in_stream4.eof()) { in_stream4 >> itemnum >> price >> curr_total; cin.clear(); cin >> next; } out_stream5.setf(ios::fixed); out_stream5.setf(ios::showpoint); out_stream5.precision(2); out_stream5 <<setw(5)<< " itemnum " <<setw(5)<<" price "<<setw(5)<<" curr_total " <<endl; // sends items and prices to receipt.txt out_stream5 << setw(5) << itemnum << setw(5) <<price << setw(5)<< curr_total; // sends items and prices to receipt.txt out_stream5 << " You have a total of " << wrong++ << " errors " << endl; }

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  • wmd editor, why does it keep showing html instead of just going straight to markup

    - by Ke
    hi, im wondering how wmd is supposed to work, when i type in the textarea the text doesnt have html, but once the text is stored in db it turns to html. wmd also shows all this html when reloading the content? is it supposed to work like this? Do I have to sanitize the text before its put into the db? if so how? I thought wmd doesnt deal with html? except in code blocks. Also there are p tags being added Using the beneath html it gets added directly. I guess this could cause xss attacks? - (1) <a onmouseover="alert(1)" href="#">read this!</a> - (2) <p <script>alert(1)</script>hello - (3) </td <script>alert(1)</script>hello I wonder how is wmd supposed to work? I thought it was supposed to enter everything in its own mark up, store its on mark up and retrieve it etc. instead of storing plain html Chees Ke

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  • When and why can sprintf fail?

    - by Srekel
    I'm using swprintf to build a string into a buffer (using a loop among other things). const int MaxStringLengthPerCharacter = 10 + 1; wchar_t* pTmp = pBuffer; for ( size_t i = 0; i < nNumPlayers ; ++i) { const int nPlayerId = GetPlayer(i); const int nWritten = swprintf(pTmp, MaxStringLengthPerCharacter, TEXT("%d,"), nPlayerId); assert(nWritten >= 0 ); pTmp += nWritten; } *pTaskPlayers = '\0'; If during testing the assert never hits, can I be sure that it will never hit in live code? That is, do I need to check if nWritten < 0 and handle that, or can I safely assume that there won't be a problem? Under which circumstances can it return -1? The documentation more or less just states "If the function fails". In one place I've read that it will fail if it can't match the arguments (i.e. the formatting string to the varargs) but that doesn't worry me. I'm also not worried about buffer overrun in this case - I know the buffer is big enough.

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  • why does entity framework+mysql provider enumeration returns partial results with no exceptions

    - by Freddy Rios
    I'm trying to make sense of a situation I have using entity framework on .net 3.5 sp1 + MySQL 6.1.2.0 as the provider. It involves the following code: Response.Write("Products: " + plist.Count() + "<br />"); var total = 0; foreach (var p in plist) { //... some actions total++; //... other actions } Response.Write("Total Products Checked: " + total + "<br />"); Basically the total products is varying on each run, and it isn't matching the full total in plist. Its varies widely, from ~ 1/5th to half. There isn't any control flow code inside the foreach i.e. no break, continue, try/catch, conditions around total++, anything that could affect the count. As confirmation, there are other totals captured inside the loop related to the actions, and those match the lower and higher total runs. I don't find any reason to the above, other than something in entity framework or the mysql provider that causes it to end the foreach when retrieving an item. The body of the foreach can have some good variation in time, as the actions involve file & network access, my best shot at the time is that when the .net code takes beyond certain threshold there is some type of timeout in the underlying framework/provider and instead of causing an exception it is silently reporting no more items for enumeration. Can anyone give some light in the above scenario and/or confirm if the entity framework/mysql provider has the above behavior? Update: I can't reproduce the behavior by using Thread.Sleep in a simple foreach in a test project, not sure where else to look for this weird behavior :(.

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  • why libxml2 quotes starting double slash in CDATA with javascript

    - by Vincenzo
    This is my code: <?php $data = <<<EOL <?xml version="1.0"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <script type="text/javascript"> //<![CDATA[ var a = 123; // JS code //]]> </script> </html> EOL; $dom = new DOMDocument(); $dom->preserveWhiteSpace = false; $dom->formatOutput = false; $dom->loadXml($data); echo '<pre>' . htmlspecialchars($dom->saveXML()) . '</pre>'; This is result: <?xml version="1.0"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <script type="text/javascript"><![CDATA[ //]]><![CDATA[ var a = 123; // JS code //]]><![CDATA[ ]]></script></html> If and when I remove the DOCTYPE notation from XML document, CDATA works properly and leading/trailing double slash is not turned into CDATA. What is the problem here? Bug in libxml2? PHP version is 5.2.13 on Linux. Thanks.

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  • Why does this regular expression fail?

    - by Stephen
    I have a password validation script in PHP that checks a few different regular expressions, and throws a unique error message depending on which one fails. Here is an array of the regular expressions and the error messages that are thrown if the match fails: array( 'rule1' => array( '/^.*[\d].*$/i', 'Password must contain at least one number.' ), 'rule2' => array( '/^.*[a-z].*$/i', 'Password must contain at least one lowercase letter' ), 'rule3' => array( '/^.*[A-Z].*$/i', 'Password must contain at least one uppercase letter' ), 'rule4' => array( '/^.*[~!@#$%^&*()_+=].*$/i', 'Password must contain at least one special character [~!@#$%^&*()_+=]' ) ); For some reason, no matter what I pass through the validation, the "Special Characters" rule fails. I'm guessing it's a problem with the expression. If there's a better (or correct) way to write these expressions, I'm all ears!

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  • mysql query - syntax error - cannot find out why

    - by Phil Jackson
    Hi all, im taring my hair out over this one. A query is throwing an error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM, SUBJECT, DATE, READ, MAIL ) VALUES ( 'EJackson', 'dfdf', '1270974101', 'fa' at line 1 I printed out the query to see what could be the problem: INSERT INTO db.tablename ( FROM, SUBJECT, DATE, READ, MAIL ) VALUES ( 'EJackson', 'dfdf', '1270974299', 'false', 'dfdsfdsfd' ) and finaly the structure consists of: CREATE TABLE db.tablename ( `ID` int(12) NOT NULL auto_increment, `FROM` varchar(255) NOT NULL, `SUBJECT` varchar(255) NOT NULL, `DATE` varchar(255) NOT NULL, `READ` varchar(255) NOT NULL, `MAIL` varchar(255) NOT NULL, PRIMARY KEY (`ID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; I cant find anything wrong. Any Help would be much appreciated. ( db.tablename is a replacement for the actual tablename )

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  • Firebug kills -webkit Settings in CSS File - Why?

    - by Johnny
    style.css - Original File .box { -webkit-border-radius:8px; -moz-border-radius:8px; padding:10px; } style.css - In Firebug CSS Console .box { -moz-border-radius:8px 8px 8px 8px; padding:10px; } How can I force Firebug to show my -webkit css styles as well? Thanks for your help!

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