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();
}