Boost random numbers - weird compilation error

Question

In a simulation I'm writing I have a class that represents an Agent that must take some actions and I want this agent to have access to a random number generator. I heard boost rng's where good ones, so I wanted to learn how to use them.

So, here's the problem. This code compiles and runs perfectly:

//Random.cpp
#include <boost/random.hpp>      
#include <boost/limits.hpp>
#include <iostream>
#include <ctime>         


int main()
{
  int N = 10;
  boost::lagged_fibonacci607 rng;
  rng.seed(static_cast<boost::uint32_t> (std::time(0)));
  boost::uniform_real<> uni(0.0,1.0);
  boost::variate_generator<boost::lagged_fibonacci607&, boost::uniform_real<> >   uniRng(rng, uni);

  for (int i = 0; i < N; ++i)
      std::cout << uniRng() << std::endl;

  return 0;

}

So, I wanted my Agent class to have access to have a private object of type:

boost::variate_generator<boost::lagged_fibonacci607&, boost::uniform_real<> > 

that can be called when the agent needs a random number.

So what I tried to do is:

//RandomAgent.cpp    
#include <boost/random.hpp>      
#include <boost/limits.hpp>
#include <iostream>
#include <ctime>         

class Agent {
private:
  boost::lagged_fibonacci607 rng;
  boost::uniform_real<> uni(0.0,1.0);
  boost::variate_generator<boost::lagged_fibonacci607&, boost::uniform_real<> >   uniRng(rng, uni);

public:
  Agent() {
    rng.seed(static_cast<boost::uint32_t> (std::time(0)));
  }
  void show() {
    std::cout << uniRng() << std::endl;
  }
};


int main() {
  Agent foo;
  for(int i = 0; i < 10; ++i) 
    foo.show()
}

And I got the following error messages:

$ g++ RandomAgent.cpp
Random.cpp:10: error: expected identifier before numeric constant
Random.cpp:10: error: expected ‘,’ or ‘...’ before numeric constant
Random.cpp:11: error: ‘rng’ is not a type
Random.cpp:11: error: ‘uni’ is not a type
Random.cpp: In member function ‘void Agent::show()’:
Random.cpp:18: error: no matching function for call to ‘Agent::uniRng()’
Random.cpp:11: note: candidates are: boost::variate_generator<boost::lagged_fibonacci607&, boost::uniform_real

> Agent::uniRng(int, int)

Answer 1

I think you need to initialise you member variables uni and uniRng in the constructor initialisation list rather than inline where they are declared.