在课堂上隐藏RNG

时间:2010-12-04 23:48:03

标签: c++ class boost

我目前正在实施一个代表52张牌的甲板课程。它使用boost随机库来移动代表卡片的整数。

#include <iostream>
#include <fstream>
#include "constants.hpp"
#include <boost/program_options.hpp>

#include <vector>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int.hpp>
#include <boost/random/variate_generator.hpp>

boost::mt19937 gen(std::time(0));

class Deck{
    private:
        std::vector<int> cards;
        int cardpointer;
        static ptrdiff_t choosecard(ptrdiff_t i);
        ptrdiff_t (*pchoosecard)(ptrdiff_t);
    public:
        Deck();
        void shuffle();
        int pop();
};

Deck::Deck(){
    for(int i=1; i<=52; i++){
        cards.push_back(i);
    }
    cardpointer = -1;
    pchoosecard = &choosecard;
}

ptrdiff_t Deck::choosecard(ptrdiff_t i){
    boost::uniform_int<> dist(0,i);
    boost::variate_generator< boost::mt19937&, boost::uniform_int<> > cardchoice(gen, dist);
    return cardchoice();
}

void Deck::shuffle(){
    std::random_shuffle(cards.begin(), cards.end(), pchoosecard);
}

我想移动“boost :: mt19937 gen(std :: time(0));” line是该类的一部分,但是我遇到了这样的问题,因为当我将它移到类定义中时会出现这个错误:

$ make
g++ -I /usr/local/boost_1_45_0/ -c main.cpp
main.cpp:22: error: ‘std::time’ is not a type
main.cpp:22: error: expected ‘)’ before numeric constant
main.cpp:22: error: expected ‘)’ before numeric constant
main.cpp:22: error: expected ‘;’ before numeric constant
main.cpp: In static member function ‘static ptrdiff_t Deck::choosecard(ptrdiff_t)’:
main.cpp:39: error: ‘gen’ was not declared in this scope
make: *** [main.o] Error 1

3 个答案:

答案 0 :(得分:4)

如果你使它成为普通的类变量,请在构造函数中初始化它:

class Deck {
    ...
    public:
        boost::mt19937 gen;
};

Deck::Deck() : gen(std::time(0))
{
    ...
}

如果你是静态的(它看起来像你,因为你正在使用来自gen的{​​{1}},这是静态的),你仍需要在课外进行声明:

choosecard

答案 1 :(得分:2)

根据我的想法,这是猜测。您必须将定义与静态gen成员的初始化分开:

class Deck {
    static boost::mt19937 gen;
    // ...
};

boost::mt19937 Deck::gen(std::time(0));

答案 2 :(得分:0)

class Deck{
    boost::mt19937 gen;
    ...
};

Deck::Deck(): gen(std::time(0)){
...
}

Deck::Deck(uint32_t seed): gen(seed){
...
}