Recursion

Recursion

A recursive function calls itself. It's a natural fit for problems that can be broken into smaller, identical subproblems.

Every recursive function needs a base case — a condition that stops the recursion. Without it, you get infinite recursion and a stack overflow.

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

Each call adds a frame to the call stack. When the base case is reached, the stack unwinds and each frame returns its result to the caller.

int fibonacci(int n) {
  if (n <= 1) {
    return n;
  }
  return fibonacci(n - 1) + fibonacci(n - 2);
}

Recursion can be elegant, but it uses memory. Iterative solutions are often more efficient. Use recursion when it makes the code simpler to understand.