How to get relative path from absolute path

Question

There\'s a part in my apps that displays the file path loaded by the user through OpenFileDialog. It\'s taking up too much space to display the whole path, but I don\'t want

Answer 1

I'm using this:

public static class StringExtensions
{
  /// 

  /// Creates a relative path from one file or folder to another.
  /// 
  /// Absolute path.
  /// Directory that defines the start of the relative path. 
  /// The relative path from the start directory to the end path.
  public static string MakeRelativePath(this string absPath, string relTo)
  {
      string[] absParts = absPath.Split(Path.DirectorySeparatorChar);
      string[] relParts = relTo.Split(Path.DirectorySeparatorChar);

      // Get the shortest of the two paths
      int len = absParts.Length < relParts.Length
          ? absParts.Length : relParts.Length;

      // Use to determine where in the loop we exited
      int lastCommonRoot = -1;
      int index;

      // Find common root
      for (index = 0; index < len; index++)
      {
          if (absParts[index].Equals(relParts[index], StringComparison.OrdinalIgnoreCase))
              lastCommonRoot = index;
          else 
            break;
      }

      // If we didn't find a common prefix then throw
      if (lastCommonRoot == -1)
          throw new ArgumentException("The path of the two files doesn't have any common base.");

      // Build up the relative path
      var relativePath = new StringBuilder();

      // Add on the ..
      for (index = lastCommonRoot + 1; index < relParts.Length; index++)
      {
        relativePath.Append("..");
        relativePath.Append(Path.DirectorySeparatorChar);
      }

      // Add on the folders
      for (index = lastCommonRoot + 1; index < absParts.Length - 1; index++)
      {
        relativePath.Append(absParts[index]);
        relativePath.Append(Path.DirectorySeparatorChar);
      }
      relativePath.Append(absParts[absParts.Length - 1]);

      return relativePath.ToString();
  }
}