Factorial calculation is a fundamental concept in programming and mathematics. In C programming, calculating the factorial of a number is an excellent way to understand loops and recursion. This article delves into how to compute a number’s factorial in C, utilizing both iterative and recursive methods.

Understanding Factorial

The factorial of a number, usually denoted as n!, is the product of all positive integers less than or equal to n. For instance, 5! = 5 * 4 * 3 * 2 * 1 = 120. It’s important to note that the factorial of 0 is defined as 1.

Iterative Approach to Calculate Factorial

Code Explanation

The iterative method uses a loop to multiply the numbers successively.

#include <stdio.h>

long factorial(int n) {
    long fact = 1;
    for (int i = 1; i <= n; i++) {
        fact *= i;
    }
    return fact;
}

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

How It Works

In this code, the factorial function calculates the factorial of the number n. It initializes fact as 1 and multiplies it by each number from 1 to n using a for loop.

Recursive Approach to Calculate Factorial

Code Explanation

Recursion involves the function calling itself with a reduced problem size.

#include <stdio.h>

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

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

How It Works

The factorial function calls itself with n-1 until it reaches 0, where it returns 1. Each return value is multiplied with n, giving the factorial result.

Conclusion

Calculating the factorial of a number in C can be achieved through iterative or recursive methods. Both approaches are effective, but recursion offers a more elegant solution, while iteration might be more intuitive for beginners. Understanding these methods is crucial for anyone learning C programming, as they provide insights into important programming concepts like loops and recursion.

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