要交换两个数字，可以使用第三个变量，并执行算术运算符，而不使用临时变量。
设置两个变量进行交换 −
val1 = 5; val2 = 10;
现在执行以下交换操作 -
val1 = val1 + val2; val2 = val1 - val2; val1 = val1 - val2;
示例
using System;
namespace Demo {
class Program {
static void Main(string[] args) {
int val1,val2;
val1 = 5;
val2 = 10;
Console.WriteLine("Values before swap...");
Console.WriteLine(val1.ToString());
Console.WriteLine(val2.ToString());
val1 = val1 + val2;
val2 = val1 - val2;
val1 = val1 - val2;
Console.WriteLine("Values after swap...");
Console.WriteLine(val1.ToString());
Console.WriteLine(val2.ToString());
Console.ReadLine();
}
}
} 
