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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 shouldnt i use flash again?

    - by acidzombie24
    I heard many times i should avoid flash for my website. Yet no one has told me a good reason. I searched for reasons and i see many that are not true (such as text in flash are not indexable by search engines) or may not necessarily be true or significant enough (eating more bandwidth. Would a JS equivalent be bigger or smaller?). My site uses flash to playback sound (m4a). I dont have to worry about indexing, the back button not working, etc. But i have feeling there may be other reasons. What are reasons i shouldnt use flash on my website. I'll note one, the fact iphone/itouch and mobile devices does not support it. Not a big deal for most sites and is obvious. What are reason to avoid flash on my site?

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  • why Cannot invoke super constructor from enum constructor ?

    - by hilal
    public enum A { A(1); private A(int i){ } private A(){ super(); // compile - error // Cannot invoke super constructor from enum constructor A() } } and here is the hierarchy of enum A extends from abstract java.lang.Enum extends java.lang.Object Class c = Class.forName("/*path*/.A"); System.out.println(c.getSuperclass().getName()); System.out.println(Modifier.toString(c.getSuperclass().getModifiers()).contains("abstract")); System.out.println(c.getSuperclass().getSuperclass().getName());

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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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  • 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 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 is debugging better in an IDE?

    - by Bill Karwin
    I've been a software developer for over twenty years, programming in C, Perl, SQL, Java, PHP, JavaScript, and recently Python. I've never had a problem I could not debug using some careful thought, and well-placed debugging print statements. I respect that many people say that my techniques are primitive, and using a real debugger in an IDE is much better. Yet from my observation, IDE users don't appear to debug faster or more successfully than I can, using my stone knives and bear skins. I'm sincerely open to learning the right tools, I've just never been shown a compelling advantage to using visual debuggers. Moreover, I have never read a tutorial or book that showed how to debug effectively using an IDE, beyond the basics of how to set breakpoints and display the contents of variables. What am I missing? What makes IDE debugging tools so much more effective than thoughtful use of diagnostic print statements? Can you suggest resources (tutorials, books, screencasts) that show the finer techniques of IDE debugging? Sweet answers! Thanks much to everyone for taking the time. Very illuminating. I voted up many, and voted none down. Some notable points: Debuggers can help me do ad hoc inspection or alteration of variables, code, or any other aspect of the runtime environment, whereas manual debugging requires me to stop, edit, and re-execute the application (possibly requiring recompilation). Debuggers can attach to a running process or use a crash dump, whereas with manual debugging, "steps to reproduce" a defect are necessary. Debuggers can display complex data structures, multi-threaded environments, or full runtime stacks easily and in a more readable manner. Debuggers offer many ways to reduce the time and repetitive work to do almost any debugging tasks. Visual debuggers and console debuggers are both useful, and have many features in common. A visual debugger integrated into an IDE also gives you convenient access to smart editing and all the other features of the IDE, in a single integrated development environment (hence the name).

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  • Why does this code sometimes return NaN?

    - by carrots
    This often returns NAN ("Not A Number") depending on input: #define PI 3.1415f GLfloat sineEaseIn(GLfloat ratio) { return 1.0f-cosf(ratio * (PI / 2.0f)); } I tried making PI a few digits smaller to see if that would help. No dice. Then I thought it might be a datatype mismatch, but float and glfloat seem to be equivalent: gl.h typedef float GLfloat; math.h extern float cosf( float ); Is this a casting issue?

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  • Why doesn't this piece of php code work?

    - by Sam Gabriel
    Hey guys, I have a mysql database which stores an id for each picture, as well as the picture's url and its thumbnail url. the thumbnail url is something like thumbs/pic.jpg and the page I'm creating has the folder thumbs in the same place it is created. But when I run this piece of code, nothing shows up: <?php ini_set('display_errors', 'On'); error_reporting(E_ALL | E_STRICT); mysql_connect("localhost", "***", "***") or die(mysql_error()); mysql_select_db("pics") or die(mysql_error()); $results = mysql_query("select id from classpics") or die(mysql_error()); $data=mysql_fetch_array($results); foreach($data as $uno) { echo '<td valign="middle" align="center"><a class="neutral" href="../images.php?id=' . $uno['id'] . '"><img src="'. $uno['thumbs'].'" border="0" /></a></td>'; } ?>

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  • Does anyone know why my maps only show grid

    - by NickTFried
    I've doubled checked my API key is right and that is right I doubled checked that it was correct. Here is my source and XML could anyone check to see what is wrong. Also I make sure I have internet. <?xml version="1.0" encoding="utf-8"?> <uses-permission android:name="android.permissions.INTERNET"/> <uses-permission android:name="android.permissions.ACCESS_FINE_LOCATION"/> <application android:icon="@drawable/icon" android:label="@string/app_name"> <uses-library android:name="com.google.android.maps" /> <activity android:name=".CadetCommand" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name="RedLight"></activity> <activity android:name="PTCalculator"></activity> <activity android:name="LandNav"></activity> </application> <uses-sdk android:minSdkVersion="4"/> package edu.elon.cs.mobile; import com.google.android.maps.MapActivity; import com.google.android.maps.MapView; import android.os.Bundle; public class LandNav extends MapActivity{ public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.landnav); } @Override protected boolean isRouteDisplayed() { return false; } }

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  • Why could Shark be so slow?

    - by taw
    I'm trying to profile Ruby interpreter. I run shark -i ./ruby bm_sudoku.rb or something like that, the script finishes in less than a second, and then Shark goes to "CHUDData - Analyzing samples... 99.3%.." point and stays there frozen for 10 minutes or so. It finishes eventually, it's just so ridiculously slow it's pretty much unusable. Version I have here is OSX 10.5, shark 4.6.1 (227). Any ideas what that might be?

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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 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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  • why it throws index out of bounds exception??

    - by Johanna
    Hi I want to use merge sort for sorting my doubly linked list.I have created 3 classes(Node,DoublyLinkedList,MergeSort) but it will throw this exception for these lines: 1.in the getNodes method of DoublyLinkedList---> throw new IndexOutOfBoundsException(); 2.in the add method of DoublyLinkedList-----> Node cursor = getNodes(index); 3.in the sort method of MergeSort class------> listTwo.add(x,localDoublyLinkedList.getValue(x)); 4.in the main method of DoublyLinkedList----->merge.sort(); this is my Merge class:(I put the whole code for this class for beter understanding) public class MergeSort { private DoublyLinkedList localDoublyLinkedList; public MergeSort(DoublyLinkedList list) { localDoublyLinkedList = list; } public void sort() { if (localDoublyLinkedList.size() <= 1) { return; } DoublyLinkedList listOne = new DoublyLinkedList(); DoublyLinkedList listTwo = new DoublyLinkedList(); for (int x = 0; x < (localDoublyLinkedList.size() / 2); x++) { listOne.add(x, localDoublyLinkedList.getValue(x)); } for (int x = (localDoublyLinkedList.size() / 2) + 1; x < localDoublyLinkedList.size(); x++) { listTwo.add(x, localDoublyLinkedList.getValue(x)); } //Split the DoublyLinkedList again MergeSort sort1 = new MergeSort(listOne); MergeSort sort2 = new MergeSort(listTwo); sort1.sort(); sort2.sort(); merge(listOne, listTwo); } public void merge(DoublyLinkedList a, DoublyLinkedList b) { int x = 0; int y = 0; int z = 0; while (x < a.size() && y < b.size()) { if (a.getValue(x) < b.getValue(y)) { localDoublyLinkedList.add(z, a.getValue(x)); x++; } else { localDoublyLinkedList.add(z, b.getValue(y)); y++; } z++; } //copy remaining elements to the tail of a[]; for (int i = x; i < a.size(); i++) { localDoublyLinkedList.add(z, a.getValue(i)); z++; } for (int i = y; i < b.size(); i++) { localDoublyLinkedList.add(z, b.getValue(i)); z++; } } } and just a part of my DoublyLinkedList: private Node getNodes(int index) throws IndexOutOfBoundsException { if (index < 0 || index > length) { throw new IndexOutOfBoundsException(); } else { Node cursor = head; for (int i = 0; i < index; i++) { cursor = cursor.getNext(); } return cursor; } } public void add(int index, int value) throws IndexOutOfBoundsException { Node cursor = getNodes(index); Node temp = new Node(value); temp.setPrev(cursor); temp.setNext(cursor.getNext()); cursor.getNext().setPrev(temp); cursor.setNext(temp); length++; } public static void main(String[] args) { int i = 0; i = getRandomNumber(10, 10000); DoublyLinkedList list = new DoublyLinkedList(); for (int j = 0; j < i; j++) { list.add(j, getRandomNumber(10, 10000)); MergeSort merge = new MergeSort(list); merge.sort(); System.out.println(list.getValue(j)); } } PLEASE help me thanks alot.

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  • Why is FLD1 loading NaN instead?

    - by Bernd Jendrissek
    I have a one-liner C function that is just return value * pow(1.+rate, -delay); - it discounts a future value to a present value. The interesting part of the disassembly is 0x080555b9 : neg %eax 0x080555bb : push %eax 0x080555bc : fildl (%esp) 0x080555bf : lea 0x4(%esp),%esp 0x080555c3 : fldl 0xfffffff0(%ebp) 0x080555c6 : fld1 0x080555c8 : faddp %st,%st(1) 0x080555ca : fxch %st(1) 0x080555cc : fstpl 0x8(%esp) 0x080555d0 : fstpl (%esp) 0x080555d3 : call 0x8051ce0 0x080555d8 : fmull 0xfffffff8(%ebp) While single-stepping through this function, gdb says (rate is 0.02, delay is 2; you can see them on the stack): (gdb) si 0x080555c6 30 return value * pow(1.+rate, -delay); (gdb) info float R7: Valid 0x4004a6c28f5c28f5c000 +41.68999999999999773 R6: Valid 0x4004e15c28f5c28f6000 +56.34000000000000341 R5: Valid 0x4004dceb851eb851e800 +55.22999999999999687 R4: Valid 0xc0008000000000000000 -2 =R3: Valid 0x3ff9a3d70a3d70a3d800 +0.02000000000000000042 R2: Valid 0x4004ff147ae147ae1800 +63.77000000000000313 R1: Valid 0x4004e17ae147ae147800 +56.36999999999999744 R0: Valid 0x4004efb851eb851eb800 +59.92999999999999972 Status Word: 0x1861 IE PE SF TOP: 3 Control Word: 0x037f IM DM ZM OM UM PM PC: Extended Precision (64-bits) RC: Round to nearest Tag Word: 0x0000 Instruction Pointer: 0x73:0x080555c3 Operand Pointer: 0x7b:0xbff41d78 Opcode: 0xdd45 And after the fld1: (gdb) si 0x080555c8 30 return value * pow(1.+rate, -delay); (gdb) info float R7: Valid 0x4004a6c28f5c28f5c000 +41.68999999999999773 R6: Valid 0x4004e15c28f5c28f6000 +56.34000000000000341 R5: Valid 0x4004dceb851eb851e800 +55.22999999999999687 R4: Valid 0xc0008000000000000000 -2 R3: Valid 0x3ff9a3d70a3d70a3d800 +0.02000000000000000042 =R2: Special 0xffffc000000000000000 Real Indefinite (QNaN) R1: Valid 0x4004e17ae147ae147800 +56.36999999999999744 R0: Valid 0x4004efb851eb851eb800 +59.92999999999999972 Status Word: 0x1261 IE PE SF C1 TOP: 2 Control Word: 0x037f IM DM ZM OM UM PM PC: Extended Precision (64-bits) RC: Round to nearest Tag Word: 0x0020 Instruction Pointer: 0x73:0x080555c6 Operand Pointer: 0x7b:0xbff41d78 Opcode: 0xd9e8 After this, everything goes to hell. Things get grossly over or undervalued, so even if there were no other bugs in my freeciv AI attempt, it would choose all the wrong strategies. Like sending the whole army to the arctic. (Sigh, if only I were getting that far.) I must be missing something obvious, or getting blinded by something, because I can't believe that fld1 should ever possibly fail. Even less that it should fail only after a handful of passes through this function. On earlier passes the FPU correctly loads 1 into ST(0). The bytes at 0x080555c6 definitely encode fld1 - checked with x/... on the running process. What gives?

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  • Why does SQLite not bring back any results from my database

    - by tigermain
    This is my first SQLite based iPhone app and I am trying to get it to read a menu hierarchy from my database. The database appears to be registered fine as the compiled statement doesnt error (tried putting in valid table name to test) but for some reason sqlite3_step(compiledStmt) doesnt ever equal SQLITE_ROW as if to suggest there is no data in there; which there is. sqlite3 *database; menu = [[NSMutableArray alloc] init]; if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { const char *sqlStmt = "SELECT * FROM Menu"; sqlite3_stmt *compiledStmt; if (sqlite3_prepare_v2(database, sqlStmt, -1, &compiledStmt, NULL) == SQLITE_OK) { while (sqlite3_step(compiledStmt) == SQLITE_ROW) { NSString *aTitle = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStmt, 1)]; MenuItem *menuItem = [[MenuItem alloc] init]; menuItem.title = aTitle; [menu addObject:menuItem]; [menuItem release]; } } else { NSLog(@"There is an error with the SQL Statement"); } sqlite3_finalize(compiledStmt); } sqlite3_close(database);

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  • Why "do...while" does not exist in F#

    - by Kev
    I cannot find "do...while..." I have to code like this: let bubbleSort a= let n = Array.length a let mutable swapped = true let mutable i = 0 while swapped do swapped <- false for j = 0 to n-i-2 do if a.[j] > a.[j+1] then let t = a.[j] a.[j] <- a.[j+1] a.[j+1] <- t swapped <- true i <- i+1 The code is bad without "do...while". Sadly, "break/continue" are also not available. Is F# not suitable for non-functional-programming?

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  • Why does this MySQL Query hang?

    - by zzapper
    SELECT * FROM tbl_order_head AS o INNER JOIN tbl_orders_log AS c ON o.PAYMENT_TRANSACTION_LOG_ID=c.TRANSACTION_ID WHERE o.VISUAL_ID = '77783'; tbl_order_head 67,000 (30 fields) records, tbl_orders_log 17000 (5 fields) records. I don't know if it would eventually return as I am running it on a live server and fear overloading. I am doing similar queries and much more complex queries successfully.

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  • Why is my number being rounded incorrectly?

    - by izb
    This feels like the kind of code that only fails in-situ, but I will attempt to adapt it into a code snippet that represents what I'm seeing. float f = myFloat * myConstInt; /* Where myFloat==13.45, and myConstInt==20 */ int i = (int)f; int i2 = (int)(myFloat * myConstInt); After stepping through the code, i==269, and i2==268. What's going on here to account for the difference?

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  • Why are Maven Goals not added by IntelliJ?

    - by Jasper
    I have produced a new Maven Project from gae-archetype-gwt from within IntelliJ, and everything is generated well, but the gae:... goals won't show up in the Maven View, and if I try to update Repository Indices, apart from the local repository I get errors only. When I run gae:unpack from terminal, everything works fine. Im running Ubuntu 10.04 Beta 1 and am using open-jdk, for which IntelliJ is also configured. UPDATE: WORKS FINE WITH UBUNTU 10.04 FINAL + JDK FROM PARTNER REPOSITORY

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