四种变量交换swap方法

1.void swap(int &x, int &y){

int temp=x;

x=y;

y=temp;

}

2.void swap(int &x, int &y){

x=x+y;

y=x-y;

x=x-y;

}

3.void swap(int &x, int &y){

x=x-y;

y=x+y;

x=y-x;

}

4.void swap(int &x, int &y){
x=x^y;

y=x^y;

x=x^y;

}