C program to find all factors of a number

Write a C program to enter any number from user and print all factors of the given number using for loop. How to find factors of any number in C programming. Logic to find all factors of a given number in C program.

Input number: 

Factors of 12: 1, 2, 3, 4, 6, 12

Required knowledge

Basic C programming, If else, For loop, Basic Mathematics

What is factor?

Factor of any number is a whole number which exactly divides any number into a whole number without leaving any remainder. For example: 2 is a factor of 6 because 2 divides 6 exactly leaving no remainder.

Logic to find factors of any number

As per definition checking divisibility is the most important task we will be doing here. You will check whether numbers from 1 to num are divisible by num or not. If divisible then it is a factor otherwise not. Read more about checking divisibility.

• Program to check divisibility of any number.

I have divided the logic to find factors of any given number to three simple steps. Let us walk by these steps.

1. Read the number from user. Store it in some variable say num.
2. Run a loop from 1 to num, incrementing 1 in each iteration. The loop structure should look like for(i=1; i<=num; i++).
3. Finally check the current loop variable is a factor of num or not. Perform modulo operation i.e. if num % i == 0 then i is a factor of num.

Program to find factors of any number

/**
 * C program to print all factors of any number
 */

#include <stdio.h>

int main()
{
    int i, num;

    /* Read a number from user */
    printf("Enter any number to find its factor: ");
    scanf("%d", &num);

    printf("All factors of %d are: \n", num);

    /* Iterate from 1 to num */
    for(i=1; i<=num; i++)
    {
        /* 
         * If num is exactly divisible by i
         * Then i is a factor of num
         */
        if(num % i == 0)
        {
            printf("%d, ",i);
        }
    }

    return 0;
} 

Enter any number to find its factors: 100

All factors of 100 are:
1, 2, 4, 5, 10, 20, 25, 50, 100,

Happy coding ;)