如何在 rand() 函数中使用枚举值答案

【问题标题】：How to use enum values in a rand() function如何在 rand() 函数中使用枚举值
【发布时间】：2017-11-18 22:55:49
【问题描述】：

如何使用生成随机枚举变量的 rand 函数？这就是我到目前为止所拥有的（它正在吐出垃圾数字）：

enum pieces { FLAG = 'F', BOMB = 'B', MARSHAL = '1', GENERAL = '2', COLONEL = 
              '3', MAJOR = '4', CAPTAIN = '5', LIEUTENANT = '6', SERGEANT = 
              '7', MINER = '8', SPY = 'S' };

int gamePieces[12] = { FLAG, BOMB, MARSHAL, GENERAL, COLONEL, MAJOR, 
                       CAPTAIN, LIEUTENANT, SEGEANT, MINOR, SPY };

int rand_piece = (rand()& gamePieces[12];

【问题讨论】：

试试gamePieces[rand() % 12]
您的代码充满了错误。错误拼写 SEGEANT，MINOR，rand_piece 中缺少右括号，枚举数为 11，而大小声明为 12。

标签： c++ random enums

【解决方案1】：

严格来说可能是不可能的。你可以

检查这些枚举的整数值是什么
那么你就可以生成一个整数了
对其进行取模 (%)
解析为枚举[编辑 - 您不必在 C++ 中将其解析为枚举]

例如。

#include <iostream>
#include <stdlib.h>  
using namespace std;

int main()
{
   enum gamePieces { FLAG, BOMB, MARSHAL, GENERAL, COLONEL, MAJOR, 
                       CAPTAIN, LIEUTENANT, SEGEANT, MINOR, SPY };

   int maxEnumValue = 12;
   int randPiece = rand() % maxEnumValue;
   cout << randPiece;
}

【讨论】：

【解决方案2】：

试试：

int main()
{
    enum pieces {
        FLAG = 'F', BOMB = 'B', MARSHAL = '1', GENERAL = '2', COLONEL =
        '3', MAJOR = '4', CAPTAIN = '5', LIEUTENANT = '6', SERGEANT =
        '7', MINER = '8', SPY = 'S'
    };

    int gamePieces[11] = { FLAG, BOMB, MARSHAL, GENERAL, COLONEL, MAJOR,
        CAPTAIN, LIEUTENANT, SERGEANT, MAJOR, SPY };


    std::cout << char(gamePieces[rand() % 11]) << std::endl;
    std::cout << char(gamePieces[rand() % 11]) << std::endl;
    std::cout << char(gamePieces[rand() % 11]) << std::endl;
    std::cout << char(gamePieces[rand() % 11]) << std::endl;
    std::cout << char(gamePieces[rand() % 11]) << std::endl;

    return 0;
}

打印：

【讨论】：

【解决方案3】：

你可以使用rand() % 12，这将创建一个0-11范围内的随机数：

int rand_piece = gamePieces[rand() % 12];

您的代码中有更多错误 - 试试这个：

#include <stdlib.h>

const int numPieces = 11;

enum pieces { FLAG = 'F', BOMB = 'B', MARSHAL = '1', GENERAL = '2', COLONEL = 
              '3', MAJOR = '4', CAPTAIN = '5', LIEUTENANT = '6', SERGEANT = 
              '7', MINER = '8', SPY = 'S' };

int gamePieces[numPieces] = { FLAG, BOMB, MARSHAL, GENERAL, COLONEL, MAJOR, 
                       CAPTAIN, LIEUTENANT, SERGEANT, MINER, SPY };

int rand_piece = gamePieces[rand() % numPieces];

或者如果你不需要额外的价值：

enum pieces { FLAG, BOMB, MARSHAL, GENERAL, COLONEL, MAJOR, 
              CAPTAIN, LIEUTENANT, SERGEANT, MINER, SPY,
              MAX_PIECE };

int rand_piece = rand() % MAX_PIECE;

【讨论】：

这是我得到的错误： ---------------------------------- ----- ex.cpp:88:44: 错误：从 'int*' 到 'int' 的无效转换 [-fpermissive] int rand_piece = gamePieces[rand() % 12];
@Gbrandonconner 您的代码中还有一些错误。查看更新的答案。