Question

1. Write a complete C++ program that at least consists of the main() function and a recursive function gcd() with return value.

• Define function gcd() with two and only two parameters that calculates the greatest common divider of two given parameters. Hint: use the difference between two parameters or the remainder obtained using one parameter divide the other.

• In main()

  1. Read 2 positive integers with proper prompt.

  2. Call gcd() with proper syntax.

  3. Display the result, i.e. the greatest common divider of two input integers, with proper prompt

Note: gcd() must be recursive functions with return value.

Answer 1

CODE:

#include <iostream>
using namespace std;
// Recursive function to return gcd of a and b
int gcd(int a, int b)
{
    //if a is zero returns the other number
    if (a == 0)
        return b;
    //if b is zero returns the other number
    if (b == 0)
        return a;

    // if both are same return anyone
    if (a == b)
        return a;

    //use the below if you want then comment out the other one.
    // gcd(b, a % b);

    // a is greater
    if (a > b)
        return gcd(a - b, b);
    return gcd(a, b - a);
}

int main()
{
    int num1, num2;
    cin >> num1 >> num2;
    cout << "GCD of " << num1 << " and " << num2 << " is " << gcd(num1, num2) << endl;
    return 0;
}