### 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