c++ - 轮盘随机数和if语句c++

Question

我正在制作轮盘赌 table ，想问一个问题，但也有人帮助我修复代码。

1，目前我使用 rand()%37 作为 0-36 数字的随机数生成器。有没有更好的生成器可以提供更多随机数？

2，我不确定如何根据 if 语句检查数组中的值。 (检查下面的代码)

int red[18] = {1,3,5,7,9,12,14,16,18,19,21,23,25,27,30,32,34,36};

int main ()
{

srand(time(NULL));
r = rand() % 3;
cout << r << endl;
for(int i = 0; i<18; i++)
    if (r==red[i])
    {
        cout << "hello" << endl;
        break;
    }
    else 
    {
        cout << "bye" << endl;
        break;
    }
return 0;
}

当我运行这段代码时，即使 r(随机数)在数组 red 中，它也会返回 bye。

致 woolstar:这是我实际代码的简化版本。我想生成一个随机数 (r)，然后根据数组 red 检查这个数字，如果 r 在数组中，我希望它被视为 true 并在这种情况下打印 hello

例如r = 14，数组中的 14 是红色的吗？是:打印你好

编辑:这是我的实际代码，当运行随机数并发现案例 B 和 C 时返回错误消息:初始化正在跳过案例标签

// Random number generator
random_device rd;
mt19937 gen (rd());

uniform_int_distribution<>
dis  (0, 36);

switch (play_method)
    {
        case 1:                                     // Color Play
        cout << "A - Play Red.\n";
        cout << "B - Play Black.\n";
        cout << "C - Play Green.\n";
        cout << "Which color will you bet on?" << endl;
        cin >> color;

        switch (color)
        {
            case 'A':                               // Red Play
                    int rred = dis(gen);
                    auto

                it = find(begin(red),end(red), rred);
                    if(it!=end(red))
                    {
                        win_amt = bet_amt*2;
                        total_amt = total_amt + (win_amt - bet_amt);
                        cout << "Congratulations you rolled a " << r << " and have won: $" << win_amt << "!" << endl;
                        cout << "You now have: $" << total_amt << " remaining." << endl;
                    }
                    else
                    {
                        total_amt = total_amt - bet_amt;
                        cout << "Unlucky, you rolled a " << r << " and have have lost  $" << bet_amt << endl;
                        cout << "You have $ " << total_amt << " remaining." << endl;
                    }           // Red play if/else end                 
            break;                                  // Break for case A: Red play

             case 'B':                              // Black play
                    int rblack = dis(gen);
                    auto

                it1 = find(begin(black),end(black), rblack);
                    if(it1!=end(black))
                    {
                        win_amt = bet_amt*2;
                        total_amt = total_amt + (win_amt - bet_amt);
                        cout << "Congratulations you rolled a " << r << " and have won: $" << win_amt << "!" << endl;
                        cout << "You now have: $" << total_amt << " remaining." << endl;
                    }
                    else
                    {
                        total_amt = total_amt - bet_amt;
                        cout << "Unlucky, you rolled a " << r << " and have have lost  $" << bet_amt << endl;
                        cout << "You have $ " << total_amt << " remaining." << endl;
                    }                   // Black play if/else end 

            break;                      // Break for case B: Black play 

            case 'C':
                int rgreen = dis(gen);
                    auto

                it2 = find(begin(green),end(green), rgreen);
                    if(it1!=end(green))
                    {
                        win_amt = bet_amt*37;
                        total_amt = total_amt + (win_amt - bet_amt);
                        cout << "Congratulations you rolled a " << r << " and have won: $" << win_amt << "!" << endl;
                        cout << "You now have: $" << total_amt << " remaining." << endl;
                    }
                    else
                    {
                        total_amt = total_amt - bet_amt;
                        cout << "Unlucky, you rolled a " << r << " and have have lost  $" << bet_amt << endl;
                        cout << "You have $ " << total_amt << " remaining." << endl;
                    }                   // Green play if/else end */
            break;

        }                               // Switch color end
        break;                          // break for case 1: Color play

Answer 1

1, currently I am using rand()%37 as my random number generator for the 0-36 numbers. Is there a better generator that gives a more random number?

绝对是的。请考虑使用 C++11 随机数工具(如果没有 C++11，则使用 Boost.Random)。

std::random_device rd;     
std::mt19937 gen(rd());
std::uniform_int_distribution<> dis { 0, 36 };

//print random number between 0 and 36
std::cout << dis(gen);

请参阅以下引用资料:

http://en.cppreference.com/w/cpp/numeric/random

2, I am unsure how to check values in an array against an if statement. (check code below)

我会使用 std::find

#include <random>
#include <iostream>
#include <algorithm>

int red[18] = {1,3,5,7,9,12,14,16,18,19,21,23,25,27,30,32,34,36};

int main () {
    std::random_device rd;     
    std::mt19937 gen { rd() };
    std::uniform_int_distribution<> dis { 0, 36 };
    int r=dis(gen);
    auto it=std::find(std::begin(red), std::end(red), r);
    if(it!=std::end(red)) {
        std::cout << "hello\n";
    }
    else {
        std::cout << "hello\n";
    }
    return 0;
}

请参阅以下引用资料:

http://en.cppreference.com/w/cpp/algorithm/find

编辑也请看这个:

希望这足以吸引人放弃 rand()。

http://channel9.msdn.com/Events/GoingNative/2013/rand-Considered-Harmful