Reverse string using C#.Net

Here i will give method for displaying reverse of string value using C#.net
ReverseValue is a method for display reverse of string.

public static string ReverseString(string str)
        {
            int length =str.Length -1;
            while (length >-1)
            {
                stringresult = stringresult + str[length];
                length--;
            }
            return stringresult;
        }
Call method : 

  string str = DerivedClass.ReverseString("LAKSHMI");

    MessageBox.Show(str.ToString());