[Qt-interest] memory problem

[Sujan Dasmahapatra]

No Bailly they are class members I wrote it like that for convenience
basically they belowng to TableWidget class

Kind Regards,
Sujan Dasmahapatra

-----Original Message-----
From: qt-interest-bounces at trolltech.com
[mailto:qt-interest-bounces at trolltech.com] On Behalf Of Yves Bailly
Sent: Tuesday, March 24, 2009 4:32 PM
Cc: qt-interest at trolltech.com
Subject: Re: [Qt-interest] memory problem

Sujan Dasmahapatra wrote:
> Dear Friends I am getting  segmentation fault for some memory 
> allocation.Could u tell  me anyone whats wrong in this code below.
> 
>
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
////////
> // In the header file:
> QList <QTableWidget *> item;
> QList <Geometry *>  geoMetry;
> int count;

Do you mean those are global variables, not class members? This is
usually seen as a very (very) bad idea.

>
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
////////
> 
> TableWidget::TableWidget()
> {
>                 count = 0;
> }
> 
> TableWidget::~TableWidget()
> {
>                 If(count != 0)

Better: if ( not item.isEmpty() )

>                 {
>                                 delete item[count];

If "count" holds the number of items (i.e. "item.size()"), then
item[count]
is one-past the last item, i.e. is invalid.

>                                 delete geoMetry[count];

Same comment.

>                 }
> }
> 
> TableWidget::fileNameUpdate(QString filename, Geometry *geometry)
> {
>                 Item[count] = new QTableWidgetItem(filename,0);

Assuming "Item" is in fact "item"...
This is wrong: initially "count" is 0 and "item" is empty. So "item[0]"
doesn't exists. So the previous line is wrong.

>                 setItem(count,0,item[count]);
>                 geoMetry[count] = new Geometry;

Same comment.

>                 geoMetry = geometry;

There I don't get at all. "geoMetry" is of type "QList<Geometry*>",
while
"geometry" is of type "Geometry*"... so they're inconsistent, you should
not
do that. Does it compiles? without even a little warning?

>                 count ++;
>  }
>
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
///////
> 
> Remember geometry and geometry are different here. geometry is a QList

> pointer and geometry is Geometry. Can u check the code and let me know

> if there's any reason for segmentation fault.The way I am deleting is 
> correct or not.?????

No it's not. Never, NEVER name a parameter using the same name as a
global
or local variable. Never, even if it's syntactically correct.

-- 
     /- Yves Bailly - Software developper  -\
     \- Sescoi France http://www.sescoi.fr -/
"The possible is done. The impossible is being done. For miracles,
thanks to allow a little delay."


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