Recursion Function

Recursion in C

What is Recursion?

Recursion is a process in which a function calls itself directly or indirectly. A function that calls itself is known as a Recursive Function.

To prevent the function from calling itself forever (which causes a "Stack Overflow"), every recursive function must have two parts:

Base Case: The condition that stops the recursion.
Recursive Case: The part where the function calls itself with a smaller or simpler input.

Syntax

        void recursiveFunction() {

            if (base_condition) {

                return; // Stop the recursion

            } else {

                recursiveFunction(); // Call itself again

            }

        }

Practical Example: Factorial of a Number

Calculating the factorial of a number ($n!$) is the most classic example of recursion. Note that $5! = 5 \times 4 \times 3 \times 2 \times 1$.

Example: Factorial Function

int factorial(int n) {
    // 1. Base Case: factorial of 0 or 1 is 1
    if (n <= 1) {
        return 1;
    }
    // 2. Recursive Case: n * factorial of (n-1)
    else {
        return n * factorial(n - 1);
    }
}

🪞 The Mirror Analogy

Imagine standing between two parallel mirrors. You see an infinite number of reflections of yourself. That is recursion without a Base Case. In programming, we use the Base Case to "break the mirror" so the program knows when to stop and return the final answer.

Recursion vs Iteration: Anything you can do with recursion, you can also do with a loop (iteration). Recursion often results in cleaner, shorter code for complex problems (like tree traversal), but loops are generally faster and use less memory.

Example

🏋️ Test Yourself With Exercises

Take our quiz on Recursion Function to test your knowledge.

Browse Quizzes »

Previous Next