Random float number generation

Question

How do I generate random floats in C++?

I thought I could take the integer rand and divide it by something, would that be adequate enough?

Answer 1

drand48(3) is the POSIX standard way. GLibC also provides a reentrant version, drand48_r(3).

The function was declared obsolete in SVID 3 but no adequate alternative was provided so IEEE Std 1003.1-2013 still includes it and has no notes that it's going anywhere anytime soon.

In Windows, the standard way is CryptGenRandom().

Answer 2

For C++, it can generate real float numbers within the range specified by dist variable

#include <random>  //If it doesnt work then use   #include <tr1/random>
#include <iostream>

using namespace std;

typedef std::tr1::ranlux64_base_01 Myeng; 
typedef std::tr1::normal_distribution<double> Mydist;

int main() { 
       Myeng eng; 
       eng.seed((unsigned int) time(NULL)); //initializing generator to January 1, 1970);
       Mydist dist(1,10); 

       dist.reset(); // discard any cached values 
       for (int i = 0; i < 10; i++)
       {
           std::cout << "a random value == " << (int)dist(eng) << std::endl; 
       }

       return (0);
}