宏定义实现两数交换

#include<stdio.h>
#define SWAP(VALUE1,VALUE2) do{    VALUE1 += VALUE2;    VALUE2 = VALUE1 - VALUE2;    VALUE1 = VALUE1 - VALUE2;}while(0)
int main()
{
    double a,b;
    a = 2;
    b = 1;
    printf("a = %lf,b = %lf\n",a,b);
    SWAP(a,b);
    printf("a = %lf,b = %lf\n",a,b);
    return 0;
}