宏定义#define

#include<stdio.h>
#define exchange(a,b){
int t;
t=a;
a=b;
b=t;
}
int main(int arge,char *argv)
{
 int a=2,b=3;
 printf("交换前a=%d,b=%d",a,b);
 exchange(a,b);
 printf("交换后a=%d,b=%d",a,b);
 return 0;
}