[Qt-interest] NewBie: How to trace Segmentation Fault in Qt?

[Srdjan Todorovic]

Hi,

On 20/07/2009, Usman Ajmal <uzmanajmal at gmail.com> wrote:
> ok i got following message after running my buggy program using gdb:
>
> (gdb) run
> Starting program: /home/usman/Memviz/QT/AnalysisModule/AnalysisModule
> [Thread debugging using libthread_db enabled]
> [New Thread 0xb6da96d0 (LWP 9320)]
>  Aspect Ratio:3.02857 Aspect Ratio:1.32075
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0xb6da96d0 (LWP 9320)]
> QGraphicsItem::scene (this=0x80f9930) at graphicsview/qgraphicsitem.cpp:839
> 839     QGraphicsScene *QGraphicsItem::scene() const

Just after you do this, can you please type in 'bt' and press return?
This will give you a stack trace and is often very useful for
debugging segmentation faults.

>           sqMap *square;
>           QStack <sqMap *> sqrBasket;
>           for(int j=0; j<=10; j++)
>                         {
>                             square = new sqMap(tempWidth, tempHeight);
>                             square->setPos(xLocation,yLocation);
>                             sqrBasket.push(square);
>                             scene->addItem(square);

I am going to guess... that scene is not initialised correctly.

Srdjan