Question

I’m trying to order a set of files base on its file name. Input is a directory with files like:

f0.vesperdp
f1.vesperdp
f2.vesperdp
....
f9.vesperdp
f10.vesperdp
f11.vesperdp
f12.vesperdp

I’ve built this LINQ query to sort them:

if (Directory.Exists(path))
{
    var directoryInfo = new DirectoryInfo(path);
    var files = from file in directoryInfo.EnumerateFiles()

    .Where(f => f.Extension == PAGE_FILE_EXTENSION)
                orderby file.Name.Substring(1, file.Name.Length - 1) ascending
                select file.FullName;

    return files.ToArray<string>();
}

But they are returning like

f0.vesperdp
f1.vesperdp
f10.vesperdp
....
f19.vesperdp
f2.vesperdp
f20.vesperdp
f21.vesperdp

I need them to be sorted using natural order (from 0 to n as f0,f1,f2...,f9,f10,f11) how can fix my orderby filter to match this? Or if there’s other way, how can I achieve that? Thanks in advance.

Answer 1

Naspinski’s correct in theory, but here’s the solution in code.

if (Directory.Exists(path))
{
    var directoryInfo = new DirectoryInfo(path);
    var files = from file in directoryInfo.EnumerateFiles()

    .Where(f => f.Extension == PAGE_FILE_EXTENSION)
                orderby int.Parse(file.Name.Substring(1, file.Name.IndexOf('.')-1)) ascending
                select file.FullName;

    return files.ToArray<string>();
}

The order-by clause basically changes to pull everything between the leading ‘f’ and the first dot, which from your examples will be a number string, which is then parsed into an integer number and displayed.