rand();

**Jamkirk** · 12-15-2007

i know there is a way to make this function:

Code:

rand();

return a completely random number using something from time.h but cant figure it out, anyone got a suggestion or an alternative?

**IdioticCreation** · 12-15-2007

Code:

srand((unsigned)time(0));

Then just call rand(); and you can use % to limit it.

I think it talks about this in the FAQ.

**Brad0407** · 12-15-2007

Everything you need to know about random numbers: FAQ

**telepatico** · 12-15-2007

I just posted a program using the system clock as the Seed, then a random generated number as follows:

Code:

//SEED THE RANDOM NUMBER WITH SYSTEM CLOCK
		srand(static_cast<unsigned int>(time(0)));

//GENERATING A RANDOM NUMBER FROM 1 - 100
		random_number = (rand() &#37; (100 - 1 + 1)) + 1;

**Brad0407** · 12-15-2007

I heard somewhere that the highest-order bits are the "most random". If you really care about that, I think this does the trick:

Code:

int RandomNumber(int min, int max)
{
	static int seeded = 0;

	if (seeded == 0)
	{
		srand(time(NULL));
		seeded = 1;
	}

	return rand() / (double)RAND_MAX * (max - min + 1) + min;
}

**dwks** · 12-15-2007

For information about high order bits and most-randomness and all that, see Prelude's article: http://eternallyconfuzzled.com/arts/jsw_art_rand.aspx

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