指针疑难问题

swap(int *p1,int *p2){
int temp;
temp=*p1;
*p1=*p2;
*p2=temp;
}
main(){
int a,b;
int *pointer_1,*pointer_2;
scanf("%d%d",&a,&b);
pointer_1=&a;
pointer_2=&b;
swap(pointer_1,pointer_2);
printf("\n%d,%d\n",a,b);
}
swap(int *p1,int *p2){
int *p;
p=p1;
p1=p2;
p2=p;
}