Convert an String to Lowercase.cs

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

namespace String32
{
    class Program
    {
        static void Main(string[] args)
        {
            string a;
            char[] b;
            int i, L;
            Console.WriteLine("Convert an String to Lower Case");
            Console.WriteLine("\n");
            Console.WriteLine("ENter the String");
            a = Console.ReadLine();
            L = a.Length;
            b = a.ToCharArray(0, L);
            for (i = 0; i < L; i++)
            {
                b[i]=(char)(b[i]+32);
                Console.Write(b[i]);
            }
            Console.ReadLine();
        }

    }
}