Program 48 - CSU1128 - CSE 2026 - Shoolini University

Program to generate factorial of the number entered by the user through function recursion

Explanation

The program calculates the factorial of a number entered by the user using a recursive function.

Header

The code begins with including the standard input-output header file using #include <stdio.h>.

Function Declaration

The program declares a recursive function factorial to calculate the factorial of a number:

int factorial(int n): Declares the function with an integer parameter n.

Function Definition

The program defines the factorial function:

if (n == 0): Defines the base case where the factorial of 0 is 1.
return 1;: Returns 1 if the base case is met.
return n * factorial(n - 1);: Defines the recursive case where the factorial of n is equal to n multiplied by the factorial of n - 1.

Variable Declaration

The main() function is defined, and a variable is declared:

int n: Variable to hold the number entered by the user.

Program Description

The program prints a description message for the user to understand its functionality.

User Input

The user is prompted to enter a number:

printf("Enter a number: ");: Prompts the user to enter a number.
scanf("%d", &n);: Reads the number and stores it in n.

Factorial Calculation

The program calculates the factorial of the number using the factorial function:

int result = factorial(n);: Calls the factorial function with n as an argument and stores the result in result.

Output Result

The program prints the factorial of the number:

printf("The factorial of %d is %d\n", n, result);: Prints the number and its factorial.

Program End

The program ends with return 0; to indicate successful execution.

Code

                    
/*
 * -----------------------------------------------------------
 * Logic Building with Computer Programming (CSU1128)
 * Instructor: Dr. Pankaj Vaidya | Author: Divya Mohan
 * 
 * This code is a part of the educational initiative by dmj.one
 * with aim of empowering and inspiring learners in the field of
 * Computer Science and Engineering through the respective courses.
 * 
 * (c) 2022, Divya Mohan for dmj.one. All rights reserved.
 * -----------------------------------------------------------
 */

#include <stdio.h>

// Declare a recursive function to calculate the factorial of a number
int factorial(int n)
{
    // Define the base case where the factorial of 0 is 1
    if (n == 0)
    {
        return 1;
    }

    // Define the recursive case where the factorial of n is equal to n multiplied by the factorial of n - 1
    return n * factorial(n - 1);
}

int main()
{
    printf("\n\n Program to generate factorial of the number entered by the user through function recursion. \n\n");

    // Declare a variable to hold the number entered by the user
    int n;

    // Read the number from the user
    printf("Enter a number: ");
    scanf("%d", &n);

    // Calculate the factorial of the number using the factorial function
    int result = factorial(n);

    // Print the result
    printf("The factorial of %d is %d\n", n, result);

    return 0;
}

Output

Program to generate factorial of the number entered by the user through function recursion.

Enter a number: 25
The factorial of 25 is 2076180480