c++ - How do I generate a random number using the C++11 standard library

Question

The new C++11 Standard has a whole chapter dedicated to random number generators. But how do I perform the simplest, most common task that used to be coded like this, but without resorting to the standard C library:

srand((unsigned int)time(0));
int i = rand();

Are there reasonable defaults for random-number engines, distributions, and seeds that one could use out of the box?

Answer 1

You should be able to do something like:

std::default_random_engine e((unsigned int)time(0));
int i = e();

The quality of the default_random_engine is implementation dependent. You could also use std::min_rand0 or std::min_rand.

Probably a better way to seed a random engine is with as true a random number as is available from the implementation rather than use time.

E.g.

std::random_device rd;
std::default_random_engine e( rd() );