Count of Matching of between two strings??

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication3
{
   public static  class Program
    {
       
           static void Main(string[] args)
           {
               string s = "ab";
               int i = s.Comparetwo("ab"); // 2
               Console.WriteLine(i); 
               Console.ReadLine();
           }
           public static int Comparetwo(this string indivi, string Tr)
           {
               int sm = 0, len = indivi.Length < Tr.Length
                    ? indivi.Length : Tr.Length;
               for (int i = 0; i < len; i++)
                   if (indivi[i] == Tr[i]) sm++;
               return sm;
           }
      
 
    }
}