C语言函数的参数使用指针

#include <stdio.h>
void swap1(int x,int y),swap2(int *px,int *py),swap3(int *px,int *py);
int main(void)
{
	int a=1,b=2;
	int *pa=&a,*pb=&b;
	swap1(a,b);
	printf("s1:a=%d,b=%d\n",a,b);
 
	a=1,b=2;
	swap2(pa,pb);
	printf("s2:a=%d,b=%d\n",a,b);
 
	a=1,b=2;
	swap3(pa,pb);
	printf("s3:a=%d,b=%d\n",a,b);
	
	return 0;
}
void swap1(int x,int y){
	int t;
	t=x;
	x=y;
	y=t;
}
 
void swap2(int *px,int *py){
	int t;
	t=*px;
	*px=*py;
	*py=t;
}
 
void swap3(int *px,int *py){
	int *pt;
	pt=px;
	px=py;
	py=pt;
}