C# Signature:

[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);

// To ensure that paths are not limited to MAX_PATH, use this signature within .NET
[DllImport("kernel32.dll", CharSet = CharSet.Unicode, EntryPoint = "GetShortPathNameW", SetLastError = true)]
static extern int GetShortPathName(string pathName, System.Text.StringBuilder shortName, int cbShortName);

VB.NET Signature:

Imports System.Runtime.InteropServices

'/// KSG Comments: This code has only been tested for .NET 2.x
   Public Class Interop
      <DllImport("kernel32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
      Public Shared Function GetShortPathName(ByVal longPath As String, _
          <MarshalAs(UnmanagedType.LPTStr)> ByVal ShortPath As System.Text.StringBuilder, _
          <MarshalAs(Runtime.InteropServices.UnmanagedType.U4)> ByVal bufferSize As Integer) As Integer
      End Function
   End Class
'OR
   Declare Unicode Function GetShortPathName Lib "kernel32.dll" Alias "GetShortPathNameW" (ByVal longPath As String, <MarshalAs(UnmanagedType.LPTStr)> ByVal ShortPath As System.Text.StringBuilder, <MarshalAs(UnmanagedType.U4)> ByVal bufferSize As Integer) As Integer

C++/CLI Signature:

  [DllImport("kernel32.dll", CharSet = CharSet::Auto, SetLastError=true)]
static int GetShortPathName(
    [MarshalAs(UnmanagedType::LPTStr)]
    String^ lpszLongPath,
    [MarshalAs(UnmanagedType::LPTStr)]
    System::Text::StringBuilder^ lpszShortPath,
    unsigned int cchBuffer);

User-Defined Types:

None.

Notes:

Important! The file must actually exist, otherwise you'll get an empty path

Tips & Tricks:

Please add some!

Sample Code:

/// <summary>
/// The ToLongPathNameToShortPathName function retrieves the short path form of a specified long input path
/// </summary>
/// <param name="longName">The long name path</param>
/// <returns>A short name path string</returns>
public static string ToShortPathName(string longName)
{
    uint bufferSize = 256;

    // don´t allocate stringbuilder here but outside of the function for fast access
    StringBuilder shortNameBuffer = new StringBuilder((int)bufferSize);

    GetShortPathName(longName, shortNameBuffer, bufferSize);

    return shortNameBuffer.ToString();
}

public string ShortPath(string longpath)
{
    char[] buffer = new char[256];

    GetShortPathName(longpath, buffer, buffer.Length);

    return new string(buffer);
}

// Memory friendly version with error checking
public static string GetShortPathName(string longFileName)
{
    int sz = GetShortPathName(longFileName, null, 0);
    if (sz == 0)
       throw new Win32Exception();
    var sb = new StringBuilder(sz + 1);
    sz = GetShortPathName(longFileName, sb, sb.Capacity);
    if (sz == 0)
       throw new Win32Exception();
    return sb.ToString();
}

VB.NET Sample Code:

/// KSG Comments:
/// Unlike the sample above I am check for the return code in the event of an error
/// KSG Changed declaration for .NET 2.x 01/25/2007
   Public Class Interop
      <Runtime.InteropServices.DllImport("kernel32.dll", SetLastError:=True, CharSet:=Runtime.InteropServices.CharSet.Auto)> _
      Public Shared Function GetShortPathName(ByVal longPath As String, _
      <Runtime.InteropServices.MarshalAs(Runtime.InteropServices.UnmanagedType.LPTStr)> _
      ByVal ShortPath As System.Text.StringBuilder, _
      <Runtime.InteropServices.MarshalAs(Runtime.InteropServices.UnmanagedType.U4)> _
      ByVal bufferSize As Integer) As Integer
      End Function
   End Class

   Function ShortPathName(ByVal Path As String) As String
      Dim sb As New System.Text.StringBuilder(1024)

      Dim tempVal As Integer = Interop.GetShortPathName(Path, sb, 1024)
      If tempVal <> 0 Then
     Dim Result As String = sb.ToString()
     Return Result
      Else
     Throw New Exception("Failed to return a short path")
      End If
   End Function

Alternative Managed API:

Do you know one? Please contribute it!

from http://social.msdn.microsoft.com/Forums/en-US/vbgeneral/thread/a036e28f-51e7-4f0c-874f-de139210e049

Neither of these works in VB2005 Express.

Ok, I have been playing with this a bit more & found a solution...this is VB2005 Express.

I was trying to put the "GetShortName" into a module and calling it from my Form (as I am used to doing). What I found, and it works for some reason, was to put this in my module:

VB.NET Signature:

Public Declare Function GetShortPathName Lib "kernel32" Alias "GetShortPathNameA" (ByVal lpszLongPath As String, ByVal lpszShortPath As String, ByVal cchBuffer As Integer) As Integer

...And I had to put this actually in the form in my event (Me.ComboBox1.DblClick):

VB.NET Sample Code:

Dim RetVal As Integer

Dim ShortFileName As String

Dim GetShortFileName As String

ShortFileName = Microsoft.VisualBasic.Space(260)

RetVal = GetShortPathName(FindMedia, ShortFileName, Microsoft.VisualBasic.Len(ShortFileName))

GetShortFileName = Microsoft.VisualBasic.Left(ShortFileName, RetVal)

MsgBox(GetShortFileName)

Spaghetti code, yes, but at least it works