文件路径

string path = "C:\dir1\dir2\foo.txt";
string str = "GetFullPath：" + Path.GetFullPath(path) + "
";
str += "GetDirectoryName：" + Path.GetDirectoryName(path) + "
";
str += "GetFileName：" + Path.GetFileName(path) + "
";
str += "GetFileNameWithoutExtension：" + Path.GetFileNameWithoutExtension(path) + "
";
str += "GetExtension：" + Path.GetExtension(path) + "
";
str += "GetPathRoot：" + Path.GetPathRoot(path) + "
";
MessageBox.Show(str);

结果： 
GetFullPath：C:dir1dir2foo.txt
GetDirectoryName：C:dir1dir2
GetFileName：foo.txt
GetFileNameWithoutExtension：foo
GetExtension：.txt
GetPathRoot：C: