using System.Runtime.InteropServices;

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

引用：
StringBuilder shortPath = new StringBuilder(80);
int result = GetShortPathName(
@"F:\1234567891.jpg", shortPath, shortPath.Capacity);
string s = shortPath.ToString();
MessageBox.Show(s.ToString());

结果：
F:\123456~1.jpg

转自csdn

本文转自94cool博客园博客，原文链接：http://www.cnblogs.com/94cool/archive/2009/08/31/1557319.html，如需转载请自行联系原作者