C Program To Find Factors Of A Number

Problem Analysis

To develop a C program to find the factor of a number it is required to understand the meaning of the factor of a number. Factor of a number has following characteristics:

A factor of a number on division leaves no remainder.
A factor of a number can be even in number or odd in number.
Square numbers have an odd number of factors.
Prime number has only two factors the number itself and 1.

Factors

Factors divide numbers in such a way that it leaves no remainder. For example 12 has factors – 1,2,3,4,6 and 12.

If 12 is divided by any of the six factors the answer will be a whole number. For example – 12 / 3 = 4

Square Numbers

Square of a number is obtained by repeated multiplication of the number by itself. For example, a square of 36 is obtained by multiplying 6 two times (6 x 6) and 1 is by default.

1 x 6 x 6 = 36

As it can be seen that 1 is also a factor of 36 it makes the number of factors odd.

1 x 6 x 6 ( 3 factors ) = 36

Prime Number

A prime number has only two factors 1 and itself. Prime number cannot be divided by another number.

Examples of prime numbers are: 2,3,5,7,11,13,17,19,23, and 29.

1 has only one factor and it is not a prime number.

Problem Description

The problem is – “C Program to find factors of a number”.

From problem analysis it is evident that to obtain factors of a number, the number has to be divided and checked for remainder. If the remainder is 0 then the quotient is one of the facator. To obtain other factors than number has to be divided by number 1 and itself.

To repeatedly divide the number loop is to be used. There are 3 loop in C language:

while loop
for loop
do while loop

From these 3 loops any one of the loops can be used.

Number after division has to be checked for the remainder. If the remainder is 0 then the quotient is a factor. To check this condition if statement of C language is to be used.

Solution to Problem

Following is the code to find factor of number:

C Program to find factor of a number

#include<stdio.h>
int main()
{
    int num_1,i;
    printf("Input positive integer");
    scanf("%d", &num_1);
    printf("Obtained factors are: %d", num_1);
    for(i=1;i<=num_1;i++)
    {
        if(num_1 % i == 0)
        {
            printf("  %d", i);
        }
    }
    return 0;
}

Output:

Input positive integer234

Obtained factors of 234 are:  1  2  3  6  9  13  18  26  39  78  117  234

Code Analysis

Input is taken from the user in integer variable num_1.
for loop is executed until i is false.
The number is divided by i and checked for remiander.
Modulo divide is used to obtain remainder by using the following code:
         
                             if(num_1 % i == 0)
      
      If the condition num % i is 0 then “i” is one of the factors.

The value of “i” is incremented by 1.

Conclusion

The problem was to find the factor of a number by developing a “C” program. Problem analysis section discusses the meaning of a factor of a number. Descriptions of the problem section discuss “C” programming constructs used to develop the code. Code analysis section re-visits code and discusses the working of the code.