Generating a random double between a range of values

Question

Im currently having trouble generating random numbers between -32.768 and 32.768. It keeps giving me the same values but with a small change in the decimal field. ex : 27.xx

Answer 1

I should mention if you're using a C++11 compiler, you can use something like this, which is actually easier to read and harder to mess up:

#include 
#include 
#include 


int main()
{
    //Type of random number distribution
    std::uniform_real_distribution dist(-32.768, 32.768);  //(min, max)

    //Mersenne Twister: Good quality random number generator
    std::mt19937 rng; 
    //Initialize with non-deterministic seeds
    rng.seed(std::random_device{}()); 

    // generate 10 random numbers.
    for (int i=0; i<10; i++)
    {
      std::cout << dist(rng) << std::endl;
    }
    return 0;
}

As bames53 pointed out, the above code can be made even shorter if you make full use of c++11:

#include 
#include 
#include 
#include 
#include 

int main()
{
    std::mt19937 rng; 
    std::uniform_real_distribution dist(-32.768, 32.768);  //(min, max)
    rng.seed(std::random_device{}()); //non-deterministic seed
    std::generate_n( 
         std::ostream_iterator(std::cout, "\n"),
         10, 
         [&]{ return dist(rng);} ); 
    return 0;
}