2 error find in some sample code in the documentation about the Layout Manager :
http://doc.qt.nokia.com/latest/layout.html#the-implementation-file

The Implementation File (card.cpp)

//#include "card.h"

First we define count() to fetch the number of items in the list.

QLayoutItem *CardLayout::count() const
{
        // QList::size() returns the number of QLayoutItems in the list
    return list.size();
}

should become :

The Implementation File (card.cpp)

#include "card.h"

First we define count() to fetch the number of items in the list.

int CardLayout::count() const
{
        // QList::size() returns the number of QLayoutItems in the list
    return list.size();
}