int main()
{
	//交换两个int的变量，不创建额外变量
	int a = 3;
	int b = 5;
	printf("%d %d\n", a, b);
	a = a^b;      //a=a+b
	b = a^b;      //b=a-b
	a = a^b;      //a=a-b
	printf("%d %d\n", a, b);
	return 0;
}