Segmentation fault error

[Niamita]

Hi all

I am facing a error segmentation fault in the following code

mapper = new QSignalMapper ();
 
    for(int i=0; i<obj_schedule_table->rowCount(); i++)
    {
        QWidget *widget1;
        widget1 = obj_schedule_table->cellWidget(i,3);
        QComboBox *combo = dynamic_cast<QComboBox*>(widget1->children().at(1));
        combo->setEditable(false);
 
        mapper->setMapping(combo, i);
        connect(combo, SIGNAL(activated(QString)), mapper, SLOT (map()));
    }
    connect(mapper, SIGNAL(mapped(int)), this, SLOT(set_item_combobox_type(int)));

mapper = new QSignalMapper ();

    for(int i=0; i<obj_schedule_table->rowCount(); i++)
    {
        QWidget *widget1;
        widget1 = obj_schedule_table->cellWidget(i,3);
        QComboBox *combo = dynamic_cast<QComboBox*>(widget1->children().at(1));
        combo->setEditable(false);

        mapper->setMapping(combo, i);
        connect(combo, SIGNAL(activated(QString)), mapper, SLOT (map()));
    }
    connect(mapper, SIGNAL(mapped(int)), this, SLOT(set_item_combobox_type(int)));

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I know it may be due to my code is pointing some null pointer but i am not understanding what is the cause of error.

Thanks in advance.

[Jonny174]

mapper = new QSignalMapper();
 
for (int i=0; i < obj_schedule_table->rowCount(); i++)
{
    QWidget *widget1 = obj_schedule_table->cellWidget( i, 3 );
    QComboBox *combo = dynamic_cast<QComboBox *>( widget1->children().at(1) );
 
    if (combo)
    {
      combo->setEditable( false );
      mapper->setMapping( combo, i );
      connect(combo, SIGNAL(activated(QString)), mapper, SLOT (map()));
    }
}
 
connect(mapper, SIGNAL(mapped(int)), this, SLOT(set_item_combobox_type(int)));

mapper = new QSignalMapper();
     
for (int i=0; i < obj_schedule_table->rowCount(); i++)
{
    QWidget *widget1 = obj_schedule_table->cellWidget( i, 3 );
    QComboBox *combo = dynamic_cast<QComboBox *>( widget1->children().at(1) );

    if (combo)
    {
      combo->setEditable( false );
      mapper->setMapping( combo, i );
      connect(combo, SIGNAL(activated(QString)), mapper, SLOT (map()));
    }
}

connect(mapper, SIGNAL(mapped(int)), this, SLOT(set_item_combobox_type(int)));

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widget1->children().at(1)? Maybe widget1->children().count() < 1?

[Niamita]

Does anybody help me what is wrong with above code.

[wysota]

Either widget1 or widget1->children().at(1) is an invalid pointer.

[nish]

did you tried to step debug your code?

[d_stranz]

If you don't know how to use the debugger (and if you don't, how do you expect to become a good programmer?), modify your code to tell you what's wrong:

#include <QMessageBox>
 
mapper = new QSignalMapper ();
 
if ( obj_schedule_table != 0 )
{
    for(int i=0; i<obj_schedule_table->rowCount(); i++)
    {
         QWidget * widget1 = obj_schedule_table->cellWidget(i,3);
         if ( widget1 != 0 )
         {
            QComboBox * combo = dynamic_cast<QComboBox*>(widget1->children().at(1));
            if ( combo != 0 )
           {
              combo->setEditable(false);
 
              mapper->setMapping(combo, i);
              connect(combo, SIGNAL(activated(QString)), mapper, SLOT (map()));
           }
           else
             QMessageBox::critical( this, "Error", "Pointer to combo is NULL" );
        }
         else
             QMessageBox::critical( this, "Error", "Pointer to widget1 is NULL" );
    }
}
else
     QMessageBox::critical( this, "Error", "Pointer to obj_schedule_table is NULL" );
 
connect(mapper, SIGNAL(mapped(int)), this, SLOT(set_item_combobox_type(int)));

#include <QMessageBox>

mapper = new QSignalMapper ();

if ( obj_schedule_table != 0 )
{
    for(int i=0; i<obj_schedule_table->rowCount(); i++)
    {
         QWidget * widget1 = obj_schedule_table->cellWidget(i,3);
         if ( widget1 != 0 )
         {
            QComboBox * combo = dynamic_cast<QComboBox*>(widget1->children().at(1));
            if ( combo != 0 )
           {
              combo->setEditable(false);

              mapper->setMapping(combo, i);
              connect(combo, SIGNAL(activated(QString)), mapper, SLOT (map()));
           }
           else
             QMessageBox::critical( this, "Error", "Pointer to combo is NULL" );
        }
         else
             QMessageBox::critical( this, "Error", "Pointer to widget1 is NULL" );
    }
}
else
     QMessageBox::critical( this, "Error", "Pointer to obj_schedule_table is NULL" );

connect(mapper, SIGNAL(mapped(int)), this, SLOT(set_item_combobox_type(int)));

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Which message box do you see? That should give you a clue about where to look to solve the problem.