how to extract common file path from list of file paths in c#

Question

What is the best way extract the common file path from the list of file path strings in c#?

Eg: I have a list 5 file paths in List variable, like below

c:\

Answer 1

Use the first path as the iterator seed:

using System;
using System.Collections.Generic;
using System.IO;

namespace stackoverflow1
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            List paths=new List();
            paths.Add(@"c:\abc\pqr\tmp\sample\b.txt");
            paths.Add(@"c:\abc\pqr\tmp\new2\c1.txt");
            paths.Add(@"c:\abc\pqr\tmp\b2.txt");
            paths.Add(@"c:\abc\pqr\tmp\b3.txt");
            paths.Add(@"c:\abc\pqr\tmp\tmp2\b2.txt");

            Console.WriteLine("Found: "+ShortestCommonPath(paths));

        }

        private static String ShortestCommonPath(IList list)
        {
            switch (list.Count)
            {
            case 0: return null;
            case 1: return list[0];
            default:
                String s=list[0];
                while (s.Length>0)
                {
                    bool ok=true;
                    for (int i=1;i