How to use c swap function

Question

It is OK to write swap(a,b);

There is an issue when I write swap(&c[0],&d[0]);. 

Can anyone explain why?

#include<iostream>
#include<algorithm>
using namespace std;

int main(void){
    int *a;
    int *b;
    int c[]={1,2};
    int d[]={3,4};
    a=&c[0];
    b=&d[0];
    swap(a,b);// it is ok
    //swap(&c[0],&d[0]);// it is error why
    cout<<a[0]<<" "<<b[0]<<endl;
    cin.get();
}

Answer 1

swap function

  template <class T> void swap ( T& a, T& b )
  {
     T c(a); a=b; b=c;
  }     

And a=&c[0]; b=&d[0]; after swap(a,b);

  a will pointing to d[0]
  b will pointing to c[0]

and swap(&c[0],&d[0]); the prototype does not correspond to the existing swap function. 

The necessary prototype is

swap(int*,int*)

so there is no matching function to call so the compiler throws error.