写一个程序，交换两个数

#include<stdio.h>
void swap(int *p1,int *p2)
{
int temp = *p1;
*p1 = *p2;
*p2 = temp;
}
int main()
{
int a = 10;
int b = 20;
printf("a=%d b=%d\n",a,b);
    swap(&a,&b);
printf("a=%d b=%d\n",a,b);
return 0;
}