C Program to find GCD

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What is Greatest Common Divisor?

A largest number that exactly divides two or more integers.

In general, Greatest Common Divisor (GCD) is otherwise called as Greatest Common Factor (GCF) or Highest Common Factor (HCF)

Tips: It is recommended to use our online GCD calculator for better understanding.

Examples

The following table provides few examples of GCD of the given numbers.

NumbersGCD
4, 10 2
6, 5 1
15, 30 , 45 15

GCD of Two Numbers

In the following example, we will find the GCD of the given two numbers (45, 90).

Example

C Compiler
#include <stdio.h> int main() { int num1 = 45; int num2 = 90; int gcd = 1; int i; for(i=2; i<=num1 && i<=num2; i++) { // Checks if i is factor of both integers if((num1 % i == 0) && (num2 % i == 0)) gcd = i; } printf("GCD of %d and %d: %d", num1, num2, gcd); return 0; }

GCD of any Two Given Numbers

In the following example, we will find the GCD of any two given numbers.

Example

C Compiler
#include <stdio.h> int main() { int num1, num2, i; int gcd = 1; printf("Enter (int) num1 = "); scanf("%d", &num1); printf("Enter (int) num2 = "); scanf("%d", &num2); for(i=2; i<=num1 && i<=num2; i++) { // Checks if i is factor of both integers if((num1 % i == 0) && (num2 % i == 0)) gcd = i; } printf("\nGCD of %d and %d: %d", num1, num2, gcd); return 0; }

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