编辑代码

using System;

        class Test
        {
          static int x;
          static void Main() { Foo (out x); }
          static void Foo (out int y)
          {
            Console.WriteLine (x);                      // x is 0
            y = 1;                                      // Mutate y
            Console.WriteLine (x);                      // x is 1
          }
        }