Calculate GCD / HCF of Two Numbers using Recursion

Write to calculate GCD / HCF of 2 number

(i)                 with recursion

(ii)               without recursion

#include<iostream>

using namespace std;

int HCF(int x, int y)

{

    int tmp;

    if(x<y)

    {

        tmp=x;

        x=y;

        y=tmp;//using tmp to swap x and y    

    }    

    while(x%y!=0)

    {

        tmp=x%y; //using tmp to store remainder

        y=x;

        x=tmp;    

    }

    return(y);

}

int HCF_rec(int x, int y){

    if(x%y==0)

    {

        return(y);

    }

    else

    {

        HCF(y,x%y);

    }

}

void main()

{

    int a,b,k;

cout<<"\n Enter Two Numbers: ";

cin>>a>>b;

    k=HCF(a,b);  

cout<<"\n\n Without Recursion";

    cout<<"\n\n HCF ("<<a<<","<<b<<") = "<<k<<"\n\n";

k=HCF_rec(a,b);  

cout<<"\n\n Using Recursion";

    cout<<"\n\n HCF ("<<a<<","<<b<<") = "<<k<<"\n\n";

system("pause");

}