C Program to Find the GCD and LCM of Two Integers

The post on C program calculates the GCD and LCM of two integer numbers.

GCD(Greatest Common Divisor) or HCF: Largest Integer that can divide both the numbers without any remainder or with 0 as remainder. For example, the GCD or HCF of 36 and 48 is 12.

LCM(Least Common Multiple): The LCM of two integers is the smallest positive integer that is perfectly divisible by both the numbers (without a remainder). For example, the LCM of 16 and 24 is 48.

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C Program to find HCF and LCM of two Integer Number

#include <stdio.h>

int main()
{
  int num1, num2, hcf, lcm, count = 1, small;

  printf("Enter 2 Numbers: \n");
  scanf("%d %d", &num1, &num2);

  small = (num1 < num2) ? num1 : num2;

  while (count <= small)
  {
    if (num1 % count == 0 && num2 % count == 0)
    {
      hcf = count;
    }

    count++;
  }

  lcm = (num1 *num2) / hcf;

  printf("GCD is: %d\n", hcf);
  printf("Lcm is: %d", lcm);

  return 0;
}

Output:

Enter 2 Numbers:
36
48
GCD is: 12
LCM is: 144

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C Program to find HCF and LCM using Recursion

Learn more on recursion.

#include <stdio.h>

int gcdFunction(int, int);

int main()
{
  int num1, num2, hcf, lcm;

  printf("Enter 2 number: \n");
  scanf("%d %d", &num1, &num2);

  hcf = gcdFunction(num1, num2);
  lcm = (num1 *num2) / hcf;

  printf("GCD of %d and %d: %d\n", num1, num2, hcf);
  printf("LCM of %d and %d: %d\n", num1, num2, lcm);

  return 0;
}

int gcdFunction(int x, int y)
{
  if (y == 0)
    return x;
  else
    return gcdFunction(y, x % y); //recursion
}

Output:

Enter 2 number:
36
48
GCD of 36 and 48: 12
LCM of 36 and 48: 144

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