Question

I’m in the process of attempting to learn RegEx. I’ve been tasked with generating a QPixmap out of several hundred *.png files. Ideally, it would be a PixMap matrix.

I think that QRegEx is the best way to perform this action so I can insert the pixmaps into a matrix without having to sort.

My pattern I’m trying to match:

runner_(int)_(int).png

Where the first integer has bounds [-1, 13] and the second [00, 20]. There is a leading zero on the second integer.

This is my code attempt:

    // find the png files in the thing
    QDir fileDir(iconPath);        
    QFileInfoList fileList = fileDir.entryInfoList();

    QRegExp rxlen("runner_([^\\_]{1,1}])_([^\\_]{1,1}]).png");        
    foreach (const QFileInfo &info, fileList) {
        qDebug() << info.fileName();
        int pos = rxlen.indexIn(info.fileName());
        if (pos > 1) {
            qDebug() << rxlen.cap(1);
            qDebug() << rxlen.cap(2);
        } else {
            qDebug() << "Didn't find any";
        }
    }

My question: Please help with the RegEx expression.

Please be gentle, I’m new to RegEx (started learning it about an hour ago!)

Thanks 🙂

Answer 1

{1,1} is absolutely useless, means something that’s used between 1 and 1 times, ie once. You can just write the element in the string.

Since you already have your pattern down all nice and proper, you can just build the regex straight from it:

runner_(-1|[0-9]|0+[0-9]|0*1[0123])_([0-9]|0+[0-9]|0*1[0-9]|20)\.png

Basically just writing patterns for all numbers in your range.

Edited to escape the dot.
Edited again to allow leading zeroes.