C Program to display factors of a number

In this article, we will write a C program to display factors of a number. For example, if the input number is 12, then the program should print numbers 1, 2, 3, 4, 6, 12 as output.

C program to print factors of a number

Let’s write the code that prompts user to enter a positive integer number and prints factors of the input number. The detailed explanation of the logic is provided at the end of the program.

#include <stdio.h>

int main() {
    int number, i;

    // Input the number
    printf("Enter a positive integer: ");
    scanf("%d", &number);

    // Displaying factors
    printf("Factors of %d are: ", number);
    for (i = 1; i <= number; ++i) {
        // Check if 'i' is a factor of 'number'
        if (number % i == 0) {  
            // If 'i' is a factor, print it
            printf("%d ", i);   
        }
    }

    return 0;
}

Output:

Enter a positive integer: 12
Factors of 12 are: 1 2 3 4 6 12

For the input number 12, the factors are 1, 2, 3, 4, 6, and 12. These are displayed in the output.

Explanation of the program:

The main part of the program is the logic used inside for loop.

for (i = 1; i <= number; ++i) {
    if (number % i == 0) {  // Check if 'i' is a factor of 'number'
        printf("%d ", i);   // If 'i' is a factor, print it
    }
}

1. Here, we are iterating through all the numbers starting from 1 till the number itself. In our case the number is 12, so the loop iterates from 1 to 12.
2. We divide the number by every number from 1 to 12 and check for the remainder, if the remainder is zero, it means that the current number is a factor, the printf statement then prints it.
3. If the remainder is not zero, the if condition returns false and that number doesn’t get printed.
4. This way all the number from 1 to 12 are checked and only the factors gets printed.

This loop iterates through all the integer numbers from 1 to the number itself, checking all the numbers if they are factors of the number. If a number is found factor, it prints the number and checks next number until all the numbers are checked.