Divisors in C

A divisor of a integer number is a integer which divides the given number without leaving a remainder.

In computing, finding the reminder of division of a number by another is called a modulo operation. To find the remainder of a divison in C, use the modulus operator %.

The function below checks whether or not the second integer received as argument is among the first number's divisors.

/*
 * Description:
 *  Checks if a number is divisible by another
 * Parameters:
 *  number  - the dividend
 *  divisor - integer to be checked as divisor
 * Returns:
 *  0 - if number is divisible by divisor
 *  1 - if number is not divisible by divisor
 */
int Divisor(int number, int divisor)
{
    int i = 0;
    if (divisor != 0)
    {
        if (number%divisor == 0)
        {
            return 1;
        }
    }
    return 0;
}

Example 1: checking if a number is divisible by another

#include<stdio.h>
#include<conio.h>

int Divisor(int number, int divisor);

int main(void)
{
    int number = 0, divisor = 0, ok = -1;
    printf("\n Enter the number: ");
    scanf("%d",&number);
    printf(" Enter the divisor to be checked: ");
    scanf("%d",&divisor);
    ok = Divisor(number,divisor);
    if (ok == 0)
    {
        printf("\n\t%d is not divisible by %d.",number,divisor);
    }
    else if (ok == 1)
    {
        printf("\n\t%d is divisible by %d.",number,divisor);
    }
    getch();
    return 0;
}

Output:  

Example 2: displaying all the divisors of a given number

#include<stdio.h>
#include<conio.h>

int Divisor(int number, int divisor);

int main(void)
{
    int number = 0, i = 0, ok = 0, counter = 0;
    printf("\n Enter the number: ");
    scanf("%d",&number);
    if (number > 0) //if the dividend is positive
    {
        for (i=1; i<=number; i++)
        {
            ok = Divisor(number,i);
            if (ok == 1)
            {
                if (counter == 0)
                {
                    printf("\n\t%d is divisible by: %d ",number,i);
                    counter++;
                }
                else if (counter > 0)
                {
                    printf("%d ",i);
                }
            }
        }
    }
    else if (number < 0) //if the dividend is negative
    {
        for (i=number; i<=-number; i++)
        {
            ok = Divisor(number,i);
            if (ok == 1)
            {
                if (counter == 0)
                {
                    printf("\n\t%d is divisible by: %d ",number,i);
                    counter++;
                }
                else if (counter > 0)
                {
                    printf("%d ",i);
                }
            }
        }
    }
    getch();
    return 0;
}

Output:  

Example 3: determine the number the divisors of a given number

#include<stdio.h>
#include<conio.h>

int Divisor(int number, int divisor);

int main(void)
{
    int number = 0, i = 0, counter = 0, ok = -1;
    printf("\n Enter the number: ");
    scanf("%d",&number);
    if (number > 0) //if the dividend is positive
    {
        for (i=1; i<=number; i++)
        {
            ok = Divisor(number,i);
            if (ok == 1)
            {
                counter++;
            }
        }
    }
    else if (counter < 0) //if the dividend is negative
    {
        for (i=number; i<=-number; i++)
        {
            ok = Divisor(number,i);
            if (ok == 1)
            {
                counter++;
            }
        }
    }
    printf("\n\t%d has %d divisors.",number,counter);
    getch();
    return 0;
}

Output: