Copy folder qt c ++

Nathan Miguel

How can i copy a folder to another directory?

mrjj

Hi
You can use QFile::copy to copy all files to new folder.
If you need to do it recursively, Qt has functions for that too that you can combine to a working function.
https://stackoverflow.com/questions/2536524/copy-directory-using-qt

Nathan Miguel

@mrjj tnks

Chris Kawa

@Nathan-Miguel Keep in mind that those stackoverflow solutions use recursion, which may result in (ironically) stack overflow with deeply nested directories. Also, if there's a lot of files QDir::entryList will return a large list, which might require large amount of memory.
A better solution might be using QDirIterator with QDirIterator::Subdirectories which uses resources only for one entry at a time.

J.Hilk

Since QDir & QDir::EntryList has some serious trouble with (MacOS) app-bundles, I ended up implementing the QDirIterator solution @Chris-Kawa suggested:

void copyAndReplaceFolderContents(const QString &fromDir, const QString &toDir, bool copyAndRemove = false) {
    QDirIterator it(fromDir, QDirIterator::Subdirectories);
    QDir dir(fromDir);
    const int absSourcePathLength = dir.absoluteFilePath(fromDir).length();

    while (it.hasNext()){
        it.next();
        const auto fileInfo = it.fileInfo();
        if(!fileInfo.isHidden()) { //filters dot and dotdot
            const QString subPathStructure = fileInfo.absoluteFilePath().mid(absSourcePathLength);
            const QString constructedAbsolutePath = toDir + subPathStructure;
            
            if(fileInfo.isDir()){
                //Create directory in target folder
                dir.mkpath(constructedAbsolutePath);
            } else if(fileInfo.isFile()) {
                //Copy File to target directory

                //Remove file at target location, if it exists, or QFile::copy will fail
                QFile::remove(constructedAbsolutePath);
                QFile::copy(fileInfo.absoluteFilePath(), constructedAbsolutePath);
            }
        }
    }

    if(copyAndRemove)
        dir.removeRecursively();
}