Recursion

A recursive function solves a problem by calling itself on a smaller input.

recursion.c

#include <stdio.h>

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

int main(void) {
    int n = ;
    int result = factorial(n);

    printf("factorial=%d\n", result);
    return 0;
}

#include <stdio.h>

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

int main(void) {
    int n = ;
    int result = factorial(n);

    printf("factorial=%d\n", result);
    return 0;
}

#include <stdio.h>

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

int main(void) {
    int n = ;
    int result = factorial(n);

    printf("factorial=%d\n", result);
    return 0;
}

base case The base case stops the recursion.

recursive case The recursive case calls the same function with a smaller value.