using System;

public class Program

{

    static int _number = 10;

​

    public static void Main()

    {

        ref int n = ref RefReturn(); // ref 區域變數

        n = 20;

​

        Console.WriteLine(_number); // 輸出 "20"

    }

​

    static ref int RefReturn() // ref 回傳值

    {

        return ref _number;

    }

}