A Question about QFile & QTextStream

[konalo]

A method loadFile which is a module of a program , a part of a notepad

void ImgProcessor::loadFile(QString filename)
{
    printf("file name:%s\n",filename.data());
    QFile file(filename);
    if(file.open(QIODevice::ReadOnly|QIODevice::Text))
    {
        QTextStream textStream(&file);
        while(!textStream.atEnd())
        {
           showWidget->text->append(textStream.readLine());
           // printf("read line \n");  ??????
            //printf("end\n");   ????
        }
    }
}

who can tell me ,why there are two "printf"
when i comment it ,nothing different ,
i can't understand the "printf"

[VRonin]

printf is just the "C way" of printing to standard output. it does nothing useful for the program, it just prints stuff to the console