standard way to convert to short path in .net

Question

looking for the standard bug-proofed way to convert "long names" such as "C:\Documents and settings" to their equivalent "short names" "C:\DOCUME~1"

I need this to run an external process from withing my C# app. It fails if I feed it with paths in the "long name".

FYI I believe "short path" is referred to the "8.3 name" – user17753 Aug 23 '12 at 13:27 — user17753, Aug 23 '12 at 13:27

score 23 · Answer 1 · edited May 13 '09 at 01:25

23

If you are prepared to start calling out to Windows API functions, then GetShortPathName() and GetLongPathName() provide this functionality.

See http://csharparticles.blogspot.com/2005/07/long-and-short-file-name-conversion-in.html

    const int MAX_PATH = 255;

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    public static extern int GetShortPathName(
        [MarshalAs(UnmanagedType.LPTStr)]
         string path,
        [MarshalAs(UnmanagedType.LPTStr)]
         StringBuilder shortPath,
        int shortPathLength
        );

    private static string GetShortPath(string path) {
        var shortPath = new StringBuilder(MAX_PATH);
        GetShortPathName(path, shortPath, MAX_PATH);
        return shortPath.ToString();
    }

edited May 13 '09 at 01:25

Sam Saffron

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answered Nov 03 '08 at 11:29

David Arno

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1

+1 im just integrating an exe that only works with shortpaths (due to an internal bug) – Sam Saffron May 13 '09 at 01:23
3

This seems to fail (returns nothing) if you pass it a path that is greater than `MAX_PATH` to be shortened. – user17753 Aug 23 '12 at 14:00
I think the strings should be marshalled as `LPWStr` instead of `LPTStr`. – unknown6656 Jul 04 '20 at 11:29
whether LPWStr or LPTStr, this method just returns the original (long) filename for me – mcmillab Aug 20 '23 at 06:50

score 4 · Answer 2 · answered Sep 26 '13 at 13:17

The trick with GetShortPathName from WinAPI works fine, but be careful when using very long paths there.

We just had an issue when calling 7zip with paths longer than MAX_PATH. GetShortPathName wasn't working if the path was too long. Just prefix it with "\?\" and then it will do the job and return correctly shortened path.

score 4 · Accepted Answer · answered Nov 03 '08 at 12:03

4

Does the external process fail even if you enclose the long file paths in quotes? That may be a simpler method, if the external app supports it.

e.g.

myExternalApp "C:\Documents And Settings\myUser\SomeData.file"

answered Nov 03 '08 at 12:03

ZombieSheep

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It works. Do you have any explanation or documentation that explains what happens? – Hanan Nov 03 '08 at 12:55
Not really. It's just (reasonably) standard behaviour for modern apps to accept arguments with spaces if the string is delimited with quotes... – ZombieSheep Nov 03 '08 at 14:35
2

You need the quotes because the path is basically a command line option, and space is the delimiter for command line options. If you use a path with spaces in it, then the command line will be parsed into multiple options. Definition: "Space" - the ASCII character often mistaken for the absence of a character – Tim Long May 13 '09 at 01:35

standard way to convert to short path in .net

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