Necessary and Sufficient

Question: The string type in C# doesn't have a Reverse() method. How would you write it?

Answer: The answer is fairly straightforward - convert the string to a char array then use a standard swap routine on the first half of the characters. Here's the C# code to do it:

        public static void Main()
        {
            string aa = "damien";
            aa = ReverseString(aa);
            Console.WriteLine(aa);
        }

        public static string ReverseString(string s)
        {
            var chars = s.ToCharArray();
            var n = chars.Length;

            for(var i=0; i<n/2; i++)
            {
                var temp = chars[i];
                chars[i] = chars[n - 1 -i];
                chars[n - 1- i] = temp;
            }
            return new string(chars);
        }