Better random algorithm?

Question

I\'m making a game in C++ and it involves filling tiles with random booleans (either yes or no) whether it is yes or no is decided by rand() % 1. It doesn\'t fe

Answer 1

True randomness often doesn't seem very random. Do expect to see odd runs.

But at least one immediate thing you can do to help is to avoid using just the lowest-order bit. To quote Numerical Recipes in C:

If you want to generate a random integer between 1 and 10, you should always do it by using high-order bits, as in

j = 1 + (int) (10.0 * (rand() / (RAND_MAX + 1.0)));

and never by anything resembling

j = 1 + (rand() % 10);

(which uses lower-order bits).

Also, you might consider using a different RNG with better properties instead. The Xorshift algorithm is a nice alternative. It's speedy and compact at just a few lines of C, and should be good enough statistically for nearly any game.

Answer 2

With random numbers to get good results you really need to have a generator that combines several generators's results. Just discarding the bottom bit is a pretty silly answer.

multiply with carry is simple to implement and has good results on its own and if you have several of them and combine the results you will get extremely good results. It also doesn't require much memory and is very fast.