Comparing Loop and Recursive Functions

Factorial, meaning the product of all positive integers up to a specified number, can be implemented in code using either loops or recursive functions.

In this lesson, we will explore how to calculate factorials using loops and recursive functions.

To calculate a factorial using a loop, you can utilize a for loop to sequentially multiply numbers from 1 to n, as shown below.

Copy
def factorial_iterative(n):
    result = 1
    for i in range(1, n + 1):
        result *= i
    return result

print(factorial_iterative(5))
# 120

To calculate a factorial using a recursive function, the function can call itself, as demonstrated in the example below.

Copy
def factorial_recursive(n):
    if n == 1:
        return 1
    else:
        return n * factorial_recursive(n - 1)

print(factorial_recursive(5))
# 120

While both the loop and recursive function implementations produce the same factorial result, there are distinct differences between the two methods:

• Speed: Generally, loops are faster than recursive functions. Recursive functions can be slower as they continually call themselves internally.

• Memory Usage: Recursive functions often use more memory because they keep calling themselves repeatedly.

Recursive functions have the advantage of being concise and easy to understand, but they may not perform as well as loops, making careful consideration necessary when choosing which to use.