How to set Font for widgets in the parent from a child widget

[ramsailesh]

Thanks Lykurg and SantoshReddy.

[ChrisW67]

Your segmentation faults come from assuming pointers are valid and point to things of certain types:

void Class::UpdateFont()
{
    QObject *obj = this->parent();  // this can be NULL
    QObjectList objlistChildren = obj->children();  // which will crash here
    int iCount = objlistChildren.count();
 
    for(int iIndex = 0; iIndex < iCount; iIndex++)
    {
        QObject *temp = objlistChildren[iIndex];
        ( (QWidget*)objlistChildren[iIndex] )->setFont(font); // what do you suppose happens if the child is not a QWidget?
    }
}

void Class::UpdateFont()
{
    QObject *obj = this->parent();  // this can be NULL
    QObjectList objlistChildren = obj->children();  // which will crash here
    int iCount = objlistChildren.count();

    for(int iIndex = 0; iIndex < iCount; iIndex++)
    {
        QObject *temp = objlistChildren[iIndex];
        ( (QWidget*)objlistChildren[iIndex] )->setFont(font); // what do you suppose happens if the child is not a QWidget?
    }
}

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You should get out of the habit of using C-style casts preferring C++-style casts of the correct type. Casts in general are last-resort mechanisms and worthy of avoidance. In this circumstance you could use qobject_cast and check the cast was successful.