Question

I used std::variate_generator in the following way in a VS2010 project:

#include <random>
...
using std::variate_generator;
using std::mt19937;
using std::uniform_real_distribution;

typedef mt19937                                     Engine;
typedef uniform_real_distribution<float>            Distribution;
typedef variate_generator< Engine, Distribution >   Generator;  

Generator r( Engine((DWORD)time(NULL)), Distribution(0.0f, 1.0f) ); 

// from now, calling float rnd = r() gave me a random number between 0.0f and 1.0f in rnd.

I’ve now put this code into a VS2012 solution and the error message I’m getting is that std::variate_generator is not a member of std.

Has std::variate_generator moved or been removed?

Answer 1

variate_generators aren’t used in the final standard version of <random>. variate_generator was part of tr1 but never made it into the standard, so I’m a bit surprised std::variate_generator worked in VS2010 (as opposed to std::tr1::variate_genrator). I believe it still exists in VS2012’s tr1 namespace though.

You can do the following instead:

#include <random>
#include <functional> // for std::bind
...
using std::mt19937;
using std::uniform_real_distribution;

typedef mt19937                                     Engine;
typedef uniform_real_distribution<float>            Distribution;

auto r = std::bind(Distribution(0.0f, 1.0f), Engine((DWORD)time(NULL)));

// from now, calling float rnd = r() gave me a random number between 0.0f and 1.0f in rnd.