QFile map file into memory

QtFileMap.cpp

#include <QCoreApplication>
#include <QFile>
#include <QDir>
#define Size 150 * 2096

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QDir dir;
    dir.mkdir("video");
    QString fileName = dir.absoluteFilePath("video/test.dat");
    QFile file(fileName);
    file.open(QFile::ReadWrite);

    uchar colors[Size];
    for(int i = 0; i < Size; i++) {
        colors[i] = uchar(i);
    }
    file.resize(Size);
    uchar *filemap = file.map(0, Size);
    memcpy(filemap, colors, Size);
    file.unmap(filemap);
    file.close();

    return 0;
//    return a.exec();
}