How to shorten a path in c# and keep it valid

Question

I work in a place where directories have such a looong name and are in such a looong tree.

And I'm having problems with too long path names for folders in an external applicatoin (I can't change this external application, but I can give it shortened path names).

I know Microsoft operating systems can shorten path names such as transforming C:\TooLongName\TooLongSubDirectory in something like C:\TooLon~1\TooLon~1.

But how can I do this in C# and still keep the nave valid and usable?

PS: I'm not using the standard FileInfo and DirectoryInfo classes, I'm using just strings that will be sent to an external application that I cannot change in any way.

Can you just update your app to allow long filenames instead? Which OS will it be running on? — DavidG, Aug 07 '17 at 14:54
I can't change anything in the external application. I just want to learn how to shorten a path (and I'll give the shortened path to the external application). — Daniel Möller, Aug 07 '17 at 14:56
This? https://stackoverflow.com/questions/258367/standard-way-to-convert-to-short-path-in-net — DavidG, Aug 07 '17 at 14:58

score 2 · Accepted Answer · answered Aug 07 '17 at 15:09

If you are unable to use the long path support build into Windows 10 you are able to use the Win32 command GetShortPathName . In order to generate a suitable path.

class Program
{
    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern uint GetShortPathName(
       [MarshalAs(UnmanagedType.LPTStr)]
       string lpszLongPath,
       [MarshalAs(UnmanagedType.LPTStr)]
       StringBuilder lpszShortPath,
       uint cchBuffer);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern uint GetShortPathName(string lpszLongPath, char[] lpszShortPath, int cchBuffer);

    static void Main(string[] args)
    {
        StringBuilder builder = new StringBuilder(260);
        var shortPath = GetShortPathName(@"C:\Projects\Databases\ReallllllllllllllyLOOOOOOOOOOOOOOOOOOOOOONGPATHHHHHHHHHHH\StillllllllllllllllllGOoooooooooooooooooooooooing", builder, (uint)builder.Capacity);
        Console.WriteLine(builder.ToString());
        Console.ReadKey();
    }
}

Produces C:\Projects\DATABA~1\REALLL~1\STILLL~1

Sounds like the right way indeed, but it's always returning an empty string. — Daniel Möller, Aug 07 '17 at 16:18
It works with folders in the computer, but not with folders starting with @"\\", such as network folders. — Daniel Möller, Aug 07 '17 at 16:28
I dont believe you can shorten UNC shares. But you might be able to mount UNC share further down the tree. — Darren, Aug 07 '17 at 21:52

How to shorten a path in c# and keep it valid

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