C++ Program to Find GCD of Two Numbers using While loop | Function | Recursion

C++ program to find gcd of two numbers using while loop, function, and recursion.

In this article, you will learn how to make a C++ program to find gcd of two numbers using while loop, function, and recursion.

 

Example

 

You should have the knowledge of the following topics in c++ programming to understand these programs:

• C++ main() function
• C++ cin object
• C++ cout object
• C++ For loop
• C++ While loop
• C++ Functions
• C++ Recursion

 

What is GCD Number?

 

In this article, we solve this problem in four methods:

1. Using the for loop
2. Using the while loop
3. Using the functions
4. Using the recursion

 

Source Code

// C++ Program to Find GCD of Two Numbers using For loop
#include <iostream>
using namespace std;

int main() {
    int p, q, i, g;
    // p & q - To store the two positive numbers
    
    cout << "-----Enter the two positive integer numbers-----\n";
    cin >> p >> q;

    for (i = 1; i <= p && i <= q; ++i) {
        if (p % i == 0 && q % i == 0) {
            g = i;
        }
    }

    cout << "\nThe GCD number of " << p << " & " << q << " is: " << g << "\n";
    return 0;
}

Run Program

Output

 

Explanation

In this given program, we have taken two inputs 180 and 50 from the user via the system console. Then we applied calculation to solve this problem.

After the above calculation, this will return 10 the final output of the above program.

 

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C++ Program to Find GCD of Two Numbers using While loop

// C++ Program to Find GCD of Two Numbers using While loop
#include <iostream>
using namespace std;

int main() {
    int p, q;
    // p & q - To store the two positive numbers
    
    cout << "-----Enter the two positive integer numbers-----\n";
    cin >> p >> q;

    while (p != q) {
        if (p > q) {
            p -= q;
        } else {
            q -= p;
        }
    }

    cout << "\nThe GCD number is: " << p << "\n";
    return 0;
}

Run Program

 

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C++ Program to Find GCD of Two Numbers using Function

// C++ Program to Find GCD of Two Numbers using Function
#include <iostream>
using namespace std;

// This function will find the GCD number
void FindGCD(int x, int y) {
    int gcd, i;

    for (i = 1; i <= x && i <= y; ++i) {
        if (x % i == 0 && y % i == 0) {
            gcd = i;
        }
    }
    cout << "\nThe GCD number of " << x << " & " << y << " is: " << gcd << "\n";
}

// It's the driver function
int main() {
    int p, q;
    // p & q - To store the two positive numbers
    
    cout << "-----Enter the two positive integer numbers-----\n";
    cin >> p >> q;

    FindGCD(p, q);
    return 0;
}

Run Program

Output

 

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C++ Program to Find GCD of Two Numbers using Recursion

// C++ Program to Find GCD of Two Numbers using Recursion
#include <iostream>
using namespace std;

// This function will do recursive
int FindGCD(int x, int y) {
    if (y != 0)
        return FindGCD(y, x % y);
    else
        return x;
}

// It's the driver function
int main() {
    int p, q;
    // p & q - To store the two positive numbers
    
    cout << "-----Enter the two positive integer numbers-----\n";
    cin >> p >> q;

    cout << "\nThe GCD number of " << p << " & " << q << " is: " << FindGCD(p, q);
    cout << endl;
    return 0;
}

Run Program

 

Also, visit these links

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