.net 匿名delegate 可以修改的局部变量

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

namespace ConsoleApplication5
{
    class Program
    {
        public delegate string F(int i);
        static void Main(string[] args)
        {
            F f = null;
            f = NewMethod(f);
            f(20);
            Console.ReadLine();
        }

        private static F NewMethod(F f)
        {
            int a = 20;
            f = delegate(int i) { Console.WriteLine(a); a = 30; return i.ToString(); };
            Console.WriteLine(a);
            Exec(f);
            Console.WriteLine(a);
            a = 10;
            return f;
        }

        static void Exec(F f)
        {
            Console.WriteLine(f(10));
        }
    }
}