Working with C++ code with QT Libraries, Read .txt File

[vitaR]

Hi, I'm having a problem with a project.

In this project I have to read some values from a .txt file, and then I have to deploy some images in a window.
I have to count every line (row) of this .txt file and colums, to show a maze with images. But Seems that my function to read this values is not working, so I guess it have to be some kind of compatibility between c++ code and QT code.

There's the code:

1. To read the size of the maze and create it.
   @void Window::tamMat(){
   fstream inFile;
   int num;
   n=m=0; //attributes of the Window Class
   inFile.open("mat.txt",ios::in);
   string line;

getline(inFile,line);
stringstream temp(line);
while(temp >> num)
m++;
n++;
while(getline(inFile,line))
n++;
inFile.close();
mat = new int*[n];
for(int i=0;i<n;i++)
mat[i]=new int[m]; //mat is a bidimensional array, I'm creating the size with the values I count from the .txt file
this->show();
}@

2)(TESTING ONLY) Try to Show in the frame 'n' numbers of images, with the value that got 'n' in the tamMat() function.
@void Window::load(){
container = new QWidget();
QPixmap icon("E:/Data/Pictures/PixelArt/Limon.png");
QPixmap icon2("E:/Data/UNET/EstructuraDeDatos/Qt/NewOne/Image/Background.png");
QGraphicsScene *scene = new QGraphicsScene();
scene->setSceneRect(0.0,0.0,800.0,600.0);
for(int i=0;i<this->n;i++){
QGraphicsPixmapItem image = new QGraphicsPixmapItem();
image->setPixmap(icon);
scene->addItem(image);
image->setPos(iicon.width(),0);
}
QTransform transform;
QGraphicsPixmapItem image2 = qgraphicsitem_cast<QGraphicsPixmapItem>(scene->itemAt(180,0,transform));
scene->addItem(image2);
QGraphicsView *view = new QGraphicsView();
view->setScene(scene);
view->show();
}@

The thing is that seems that the int value 'n', Still zero(0), cause there's no image in this frame. So the for loop, never happen (check load() Function).
I don't know if I can't work with C++ library while I'm working with the QT Ones. Could be this the problem?

Thanks for your time. By the way, I have to work with some functions in c++ code, like fstream library, work with data structures, like piles, some kind of that stuff, any advice you can give me to avoid future errors, would be great, thanks.