C Language: finding factorial of a number using looping

Following sample program shows how to find the factorial of a number using looping.

This code is released under the terms of GNU General Public License.

/*
 * Copyright (C) 2009 Raghavendra Nayak
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>

/**
* @brief function to find the factorial of a number.
*
* This function returns number! (the factorial of number).
* For negative number, number! is defined to be 1.
*
* @param[in] number    the number for which you want to find the factorial.
* @return  The factorial of the @sa number.
*
* Note: This function uses a loop to find the factorial.
*/
int factorial(const int number)
{
int result = 1;
int i;
for (i = 1; i <= number; i++) {
result *= i;
}
return result;
}

int main(void)
{
int number;
int factorial_of_number;

printf("\nEnter the input number: ");

scanf("%d", &number);

factorial_of_number = factorial(number);

printf("\nInput number is: %d", number);
printf("\nFactorial of %d or %d! is %d\n", number, number, factorial_of_number);

return EXIT_SUCCESS;
}

To download the project click here. or you can visit Google code project at http://code.google.com/p/nayak.

Building the project:

You can build this project using any of the following method.

1. $ gcc factorial.c -o factorial
   
2. $ make
3. $ cmake . && make

First method requires you to have gcc installed.
Second method requires you to have gcc along with the GNU make installed.
Third method requires you to have cmake along with GNU make.

To execute the compiled binary issue following command.

$ ./factorial