Question

How do you generate a random double uniformly distributed between 0 and 1 from C++?

Of course I can think of some answers, but I'd like to know what the standard practice is, to have:

• Good standards compliance
• Good randomness
• Good speed

(speed is more important than randomness for my application).

Thanks a lot!

PS: In case that matters, my target platforms are Linux and Windows.

Answer 1

An old school solution like:

double X=((double)rand()/(double)RAND_MAX);

Should meet all your criteria (portable, standard and fast). obviously the random number generated has to be seeded the standard procedure is something like:

srand((unsigned)time(NULL));