用指针实现实参值的变换

#include<iostream>
using namespace std;
int main()
{
 void exchange(int *pointer_1,int *pointer_2);
 int *pointer_1,*pointer_2;
 int a,b;
 cout<<"They are:"; 
 cin>>a>>b;
 cout<<endl;
 pointer_1=&a;
 pointer_2=&b;
 exchange(pointer_1, pointer_2);
 cout<<"They become:"<<*pointer_1<<" "<<*pointer_2<<endl;
 return 0;
}
void exchange(int *pointer_1,int *pointer_2)
{
 int t;
 t=*pointer_1;
 *pointer_1=*pointer_2;
 *pointer_2=t;
}