#代码
int number1 = 10;

int number2 = 5;

Console.WriteLine("number1=" + number1 + "，number2=" + number2); //交换前数字

number1 = number1 - number2;

number2 = number1 + number2;

Console.WriteLine("number1=" + number1 + "，number2=" + number2);//交换后数字 Console.ReadKey();

#效果

第二节课第一个作业