QT Splitting files inside folder into different subfolders

Question

I have the following code to copy files to subfolders. But always the first 20 pictures are copied instead of 1-20 into the first folder, 21-40 to the second folder and 41-60 to the third folder:

QDir dir(ui->lineEdit->text());
QList<QString> fileNameList;
QFileInfoList files = dir.entryInfoList();
foreach(const QFileInfo &fi, files) {
    if(!fi.isDir()) {
        if (fi.fileName().endsWith(".JPG")) {
            fileNameList.append(fi.fileName());
        }
    }
}

int parts = (int) (fileNameList.size()) / ui->spinBox->value();

qDebug() << "parts=" << parts;

for (int i = 0; i < parts; i++) {
    QDir().mkdir(ui->lineEdit->text() + QString("/part%1").arg(i + 1));
    for (int l = 0; l < ui->spinBox->value(); l++) {
        QFile::copy(ui->lineEdit->text() + "/" + fileNameList.at(l), ui->lineEdit->text() + QString("/part%1").arg(i + 1) + "/" + fileNameList.at(l));
    }
}

Answer 1

The problem is with the indexing of fileNameList. You are always indexing it from 0 to l Which causes to always copy the first files. It should be like :

int index = i*ui->spinBox->value() + l;
QFile::copy(ui->lineEdit->text() + "/" + fileNameList.at(index), ui->lineEdit->text() + QString("/part%1").arg(i + 1) + "/" + fileNameList.at(index));