Recursive Function in Python

What is a Recursive Function? A recursive function is a function that calls itself to solve a smaller version of the same problem.

Usually, recursion has two parts:

Base Case – stops the recursion to prevent infinite calls.
Recursive Case – the function calls itself with modified arguments.

Syntax of a Recursive Function

def function_name(parameters):
    if base_condition:
        return some_value  # Base case
    else:
        return function_name(modified_parameters)  # Recursive case

Example: Factorial of a Number.

Python

# Recursive function to calculate factorial
def factorial(n):
    # Base case: factorial of 0 or 1 is 1
    if n == 0 or n == 1:
        return 1
    else:
        # Recursive case: n * factorial of (n-1)
        return n * factorial(n - 1)

# Test the function
print(factorial(5))  # Output: 120

Explanation:

factorial(5) calls factorial(4) → factorial(3) → … until factorial(1).
Then it multiplies back: 1 → 2 → 6 → 24 → 120.

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