Recursive function example

recursive.c

#include <stdio.h>
#include <stdlib.h>

int factorial(int n);

int main(int argc, char* argv[])
{
    if(argc > 1)
    {
        int number;
        sscanf(argv[1], "%d", &number);
        fprintf(stdout, "%d! = %d\n", number, factorial(number));
    }
    else
        fprintf(stdout, "Usage: %s <number>\n", argv[0]);
    
    return 0;
}

int factorial(int n)
{
    if (n > 1)
        return n * factorial(n - 1);
    else
        return 1;
}

Thanks to quick bug report, logical error was corrected: return factorial(n - 1) replaced by return n * factorial(n - 1).

This is very basic denotation and basically works. This but needs to sanitise wrong input (not a number, number is zero or negative), so it won't crash if user inputs foo instead of a positive number and won't output a number and obviously wrong answer when the user inputs zero or a negative number. Use it only as a scheme of how it would actually be used. The only part that is actually relevant here is the recursive factorial function. This obviously only applies to this particular recursive function. It only calls itself when conditions are met and return a known value otherwise, therefore preventing infinite recursion and stack overflow.