Boost Random Number Not Change

Question

I have some problem when generating random number with boost library in CPP. When I try printout random number, the value return same value. Here is my code.

for(int i = 0; i < TOTAL_PARTICLES; i++) {
            boost::random::mt19937 engine(static_cast<unsigned int>(std::time(0)));                    
            randn = boost::bind(boost::random::uniform_real_distribution<>(-2.5, 2.5), engine);                            
            cout << "Random : " << randn() << endl;
        }

You're always using the same seed - try putting the engine out the for loop — UKMonkey, May 28 '19 at 15:10
different generator, same problem: https://stackoverflow.com/questions/9459035/why-does-rand-yield-the-same-sequence-of-numbers-on-every-run btw I found this by simply typing your title into google, hence the downvote ;) — 463035818_is_not_an_ai, May 28 '19 at 15:12

score 1 · Answer 1 · answered May 28 '19 at 18:41

You're using the same engine seed every time, and therefore you'll receive the same set of random numbers each and every time. Therefore simply seed the engine outside of the for loop like so:

boost::random::mt19937 engine(static_cast<unsigned int>(std::time(0)));                    
for(int i = 0; i < TOTAL_PARTICLES; i++) 
{
    randn = boost::bind(boost::random::uniform_real_distribution<>(-2.5, 2.5), engine);                            
    cout << "Random : " << randn() << endl;
}

Boost Random Number Not Change

1 Answers1