Magic 8 game in C.

magic8.c

/*	Magic 8 game in C
	Copyright (C) 2025  PackmanDude

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
#define _GNU_SOURCE
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

int main(int argc, char *argv[])
{
	if (!argc) return EXIT_FAILURE;
	if (argc < 2) goto fail;
	{
		const size_t last_argument_length = strlen(argv[argc - 1]);
		// Check if the last character is not a question mark
		if (!last_argument_length || argv[argc - 1][last_argument_length  - 1] != '?')
			goto fail;
	}
	{
		struct timespec ts;
		if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
		{
			perror("clock_gettime");
			return EXIT_FAILURE;
		}
		srandom(ts.tv_nsec);
	}
	{
		const char * const answers[20] =
		{
			"It is certain",
			"It is decidedly so",
			"Without a doubt",
			"Yes definitely",
			"You may rely on it",
			"As I see it, yes",
			"Most likely",
			"Outlook good",
			"Yes",
			"Signs point to yes",
			"Reply hazy, try again",
			"Ask again later",
			"Better not tell you now",
			"Cannot predict now",
			"Concentrate and ask again",
			"Don't count on it",
			"My reply is no",
			"My sources say no",
			"Outlook not so good",
			"Very doubtful"
		};
		printf("%s.\n", answers[((uint64_t)random() * 20) >> 31]);
	}
	return EXIT_SUCCESS;
fail:
	fprintf(stderr, "You need to ask first! (add a question mark at the end)\n");
	return EXIT_FAILURE;
}