Magic 8 Ball

magic8ball.m

// clang -o magic8ball -framework Foundation magic8ball.m

#import <Foundation/Foundation.h>
#include <stdio.h>

NSUInteger randomUnder(NSUInteger topPlusOne);

int main()
{
	srandomdev(); // rather important

	NSAutoreleasePool * pool0 = [[NSAutoreleasePool alloc] init];
	
	NSArray * answers = [NSArray arrayWithObjects:
		@"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",
		@"Signs point to yes",
		@"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",
		nil];
	NSUInteger items = [answers count];

	NSUInteger item = randomUnder(items);
	
	printf("%s\n", [[answers objectAtIndex:item] UTF8String]);
	
	[pool0 release];

	return 0;
}

/* see http://www.mikeash.com/pyblog/friday-qa-2011-03-18-random-numbers.html */
NSUInteger randomUnder(NSUInteger topPlusOne)
{
	unsigned two31 = 1U << 31;
	unsigned maxUsable = (two31 / topPlusOne) * topPlusOne;

	while(1)
	{
		unsigned num = random();
		if(num < maxUsable)
			return num % topPlusOne;
	}
}