//Program to find the G.C.D. of two numbers

#include<iostream.h>

#include<conio.h>

int gcd(int a, int b);

void main()

{

int x, y, g;

clrscr();

cout<<"Enter two numbers : "<<endl;

cin>>x>>y;

g=gcd(x,y);

cout<<"GCD of these numbers is : "<<g;

getch();

}

int gcd(int a, int b)

{

int r;

r=a%b;

while (r>0)

{

a=b;

b=r;

r=a%b;

}

return b;

}

getch for more older version of Turbo C++ compiler

Enter two numbers :

40

20

GCD of these numbers is : 20