/*
    gdb_test.c
    Jeff Ondich, 14 February 2022
    Major simplifications, 17 Oct 2023
    Modified by Tanya Amert for Fall 2024

    A simple recursive C program to play around with in gdb.

    Compile like this:

        gcc -o gdb_test -Wall -Werror -g -Og gdb_test.c

    Run with one command-line argument (n to compute fact(n)):

        ./gdb_test 8
*/

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

// Recursive factorial
int factorial(int n)
{
    // Base case
    if (n <= 1)
    {
        return 1;
    }

    // Recursive case
    int result = factorial(n - 1);
    result = n * result;
    return result;
}

// A reminder of how to use this program.
void print_usage(char *command_name)
{
    fprintf(stderr, "Usage: %s [integer]\n", command_name);
}

// Read in a single parameter, n, from command-line arguments
// and compute and then print out fact(n)
int main(int argc, char *argv[])
{
    // Make sure we have exactly one extra parameter
    if (argc != 2)
    {
        print_usage(argv[0]);
        return 1;
    }

    // Read in the actual value of n
    int n = 0;
    int matches = sscanf(argv[1], "%d", &n);
    if (matches != 1) // what's this about?
    {
        print_usage(argv[0]);
        return 1;
    }

    // Compute fact(n) and print the result
    int result = factorial(n);
    printf("%d! = %d\n", n, result);

    // Success!
    return 0;
}