Recursive Functions

This lesson covers writing a recursive function in C, so you understand the mechanism of a function calling itself. It's for anyone searching "C recursive function usage."

A recursive function is a function that calls itself. It's well-suited to logic that repeats the same calculation pattern, like "n! = n × (n-1)!".

The example's factorial function calls itself as n * factorial(n - 1), computing the factorial of 5. The base case, if (n <= 1) return 1;, ensures the chain of calls eventually stops.

A common early mistake is forgetting the base case. Without one, the function calls itself forever, causing the fatal error known as a stack overflow.

In real projects, C often favors rewriting recursion as a loop instead, to avoid the overhead of recursive function calls.

📖 Reference code

#include <stdio.h>

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

int main(void) {
    printf("%d\n", factorial(5));
    return 0;
}

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run C directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).