The Program in C to Calculate Factorial Using Recursive Function is given below:

#include <stdio.h>

int factorial(int n){
    if (n == 0) {
        return 1;
    }
    return n * factorial(n - 1);
}

int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    int fact = factorial(num);
    printf("The factorial of %d is %d\n", num, fact);
    return 0;
}

Output:

Enter a number: 7
The factorial of 7 is 5040

Pro-Tips💡

In this program, the function ‘factorial’ takes an integer as an argument and returns its factorial using recursion.

The function uses a base case of n = 0, where it returns 1 as the factorial of 0 is 1.

For any other value of n, the function returns the product of n and the factorial of (n-1).

This process is repeated until the base case is reached, and the final returned value is the factorial of the given number.

In main function, user is prompted to enter a number, the number is passed to the factorial function, and the result is stored in variable ‘fact’ and it is printed.

Recursive function is a function that calls itself in the function body, and it is typically used to solve problems that can be broken down into smaller sub-problems of the same kind.

Factorial is a classic example of a problem that can be solved using recursion because it can be defined recursively as the product of n and the factorial of (n-1