交换两个变量的值的几种方式
1.使用一个临时变量
int a,b;
int tmp = a;
a = b;
b = tmp;
2.使用+-运算
int a,b;
a = a+b;
b = a - b;
a = a - b;
3.使用位运算
int a,b;
a = a ^ b;
b = a ^ b;
a = a ^ b;
int a,b;
int tmp = a;
a = b;
b = tmp;
int a,b;
a = a+b;
b = a - b;
a = a - b;
int a,b;
a = a ^ b;
b = a ^ b;
a = a ^ b;