交换两个变量以及不用第三个变量交换两个变量

这个可能网上一搜一大把一大把的，可是今天我看到了一个新的写法，所以就写这篇文章记录一下，不不知道百度有没有，没去搜索！

方法1：这是最简单，也是最常用的一个方法！

            int n1 = 10, n2 = 20;
            int tmp = n1;
            n1 = n2;
            n2 = tmp;
            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey();

方法2：算术运算

            int n1 = 10, n2 = 20;
            n2 = (n1 +n2)- (n1 = n2) ;
            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey();

            //交换两个变量，不使用第三个变量
            int n1 = 10, n2 = 20;
            n1 = n1 + n2;
            n2 = n1 - n2;
            n1 = n1 - n2;
            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey();

方法3：这个是我今天要记录的重点

            int n1 = 10, n2 = 20;
            n2 = n1 + (n1 = n2) * 0;
            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey();

方法4：多写点，面试的时候，逼格又上涨了一节！

           //位运算
            int n1 = 10, n2 = 20;
            n1 = n1 ^ n2;
            n2 = n1 ^ n2;
            n1 = n1 ^ n2;

            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey();

扩展：交换两个变量，封装成方法

//这样直接交换的话，你会发现输出的值并没有变！ 
          int n1 = 10, n2 = 20;
            Swap( n1,  n2);
            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey(); 


private static void Swap( int n1,  int n2)
        {
            int tmp = n1;
            n1 = n2;
            n2 = tmp;
        }
//-----------------------------------------------------------------------------------------
//把变量前边加上“ref” 把值类型变为引用类型（不明白可以百度这两个类型的区别）
            int n1 = 10, n2 = 20;
            Swap(ref n1, ref n2);
            Console.WriteLine("n1={0},n2={1}", n1, n2);
            Console.ReadKey();


private static void Swap(ref int n1, ref int n2)
        {
            int tmp = n1;
            n1 = n2;
            n2 = tmp;
        }

　　

 续：

刚刚有想到这样一个防范，不知道算不算，用try语句

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

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int n1 = 10, n2 = 20;
            n1 = JiaoHuanN(ref n1,ref n2);
            Console.WriteLine("n1="+n1.ToString() + "      n2=" + n2.ToString());
            Console.ReadKey();
        }


      public static  int JiaoHuanN(ref int N1, ref int N2)
        {
          
            try
            {
                return  N2;

            }
            catch (Exception)
            {

                throw;
            }
            finally
            {
                N2 = N1;
            }
        }

        
    }
}