C#转换字符大小写

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

namespace Demo {
   class MyApplication {
      static void Main(string[] args) {

         string str;
         str = AMIT;
         Console.WriteLine(UpperCase : {0}, str);

         // convert to lowercase
         Console.WriteLine(Converted to LowerCase : {0}, str.ToLower());
         Console.ReadLine();
      }
   }
}