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在只使用 Python 太久之后，我正在努力重新熟悉 C++。我已经用 MS Visual C++ 2010 Express 版本编写了一个小程序，并且我到处寻找导致编译器似乎不喜欢我使用枚举类 Choice 的罪魁祸首。编译器抱怨不存在具有此名称的命名空间。现在，我应该说我之前编写的所有 C/C++ 代码都是在学术环境中，因此我使用的是完整的 IDE。无论如何，我在下面附加了代码，如果这是不正确的发布方法，请原谅我。如果是，请向我推荐正确的方法，我将在以后使用它。提前感谢您提供任何可以提供的帮助或见解。代码如下：

#include"stdafx.h"
#include<iostream>
#include<string>
#include<ctime>
using namespace std;

enum class Choice { rock, paper, scissors };
using namespace Choice;**

Choice player_choice;    //holds user's move
Choice machine_choice;   //holds machine's move

string words[3] = {"rock","paper","scissors"};

Choice get_machine_choice();
void decide_winner();
string get_msg(Choice winner);
int rand0toN1(int n);
int main(int argc, char *argv[])
{
    srand(time(NULL));    //set randomization
    string input_str;
    int c;
    while (true) {
        cout << "Enter Rock, Paper, Scissors, or Exit: ";
        getline(cin, input_str);
        if (input_str.size() < 1) {
            cout << "Sorry, I don't understand that.\n";
            continue;
        }
        c = input_str[0];
        if (c == 'R' || c == 'r')
            player_choice = rock;
        else if (c == 'P' || c == 'p')
            player_choice = paper;
        else if (c == 'S' || c == 's')
            player_choice = scissors;
        else if (c == 'E' || c == 'e')
            break;
        else {
            cout << "Sorry, I don't understand that.\n";
            continue;
        }
        machine_choice = get_machine_choice();
        int p = (int) player_choice;
        int c = (int) machine_choice;
        cout << "You Choose " << words [p];
        cout << "," << endl;
        cout << "I choose " << words [c];
        cout << "," << endl;
        decide_winner();
    }
    return EXIT_SUCCESS;
}

Choice get_machine_choice() {
    int n = rand0toN1(3);
    if (n == 0) return rock;
    if (n == 1) return paper;
    return scissors;
}

void decide_winner() {
    if (player_choice == machine_choice) {
        cout << "Reult is a tie.\n\n";
        return;
    }
    int p = static_cast<int>(player_choice);
    int c = static_cast<int>(machine_choice);
    if (p - c == 1 || p - c == -2) {
        cout << get_msg(player_choice);
        cout << "Unfortunantly, you win...\n";
    } else {
        cout << get_msg(machine_choice);
        cout << "I WIN, BEEEATCH!!!!\n";
    }
    cout << endl;
}

string get_msg(Choice winner) {
    if (winner == rock)
        return string("Rock smashes scissors, beeatch...");
    else if (winner == paper)
        return string("You know what paper does to rock, COVERAGE!!...");
    else
        return string("CHOP! Scissors cut paper!!....");
}

int rand0toN1(int n) {
    return rand() % n;
}

再次感谢您花时间帮助我。我似乎记得经常使用 C++ 声明类，但不知道为什么它不能识别它。

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4 回答 4

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VC++ 在 2010 年不支持 enum 类。你需要2012。

于 2013-05-29T16:41:42.983 回答
5

enum classVisual c++ 2010 不支持，但我认为它在 vc++ 2012 中。见这里。

您必须升级您的编译器或使用普通的“枚举”，这当然会略有不同。

于 2013-05-29T16:45:26.320 回答
1

enum 类是作为 c++11 标准的一部分引入的。它不会在VC2010中存在。您需要升级到 VC2012 才能使用此功能。否则从枚举声明中删除“类”。

enum class Choice { rock, paper, scissors }; //Error in vs2010. Drop class.
enum class Choice { rock, paper, scissors }; //Ok in vs2012.
enum Choice { rock, paper, scissors }; //Ok in vs2010.
于 2013-05-29T16:59:39.637 回答
1

所以看起来你想使用命名空间“Choice”，但你没有先定义它。要定义一个新的命名空间，可以像这样定义它：

namespace X { // namespace definition
  int a;
  int b;
  }
using namespace X; //then you can use it

但实际上，我不确定您是否需要定义任何命名空间......在您的情况下，我发现的问题是您声明了“枚举类选择”，而不是简单的“枚举选择”。例如，请阅读有关 c++ 中枚举用法的链接：http ://www.cplusplus.com/forum/beginner/44859/

我以这种方式修改了您的代码，并且运行良好：

#include"stdafx.h"
#include<iostream>
#include<string>
#include<ctime>
using namespace std;

enum Choice { 
        rock, 
        paper, 
        scissors };

Choice player_choice;    //holds user's move
Choice machine_choice;   //holds machine's move

string words[3] = {"rock","paper","scissors"};

Choice get_machine_choice();
void decide_winner();
string get_msg(Choice winner);
int rand0toN1(int n);

int main(int argc, char *argv[])
{
    srand(time(NULL));    //set randomization
    string input_str;
    int c;
    while (true) {
        cout << "Enter Rock, Paper, Scissors, or Exit: ";
        getline(cin, input_str);
        if (input_str.size() < 1) {
            cout << "Sorry, I don't understand that.\n";
            continue;
        }
        c = input_str[0];
        if (c == 'R' || c == 'r')
            player_choice = rock;
        else if (c == 'P' || c == 'p')
            player_choice = paper;
        else if (c == 'S' || c == 's')
            player_choice = scissors;
        else if (c == 'E' || c == 'e')
            break;
        else {
            cout << "Sorry, I don't understand that.\n";
            continue;
        }
        machine_choice = get_machine_choice();
        int p = (int) player_choice;
        int c = (int) machine_choice;
        cout << "You Choose " << words [p];
        cout << "," << endl;
        cout << "I choose " << words [c];
        cout << "," << endl;
        decide_winner();
    }
    return EXIT_SUCCESS;
}

Choice get_machine_choice() {
    int n = rand0toN1(3);
    if (n == 0) return rock;
    if (n == 1) return paper;
    return scissors;
}

void decide_winner() {
    if (player_choice == machine_choice) {
        cout << "Reult is a tie.\n\n";
        return;
    }
    int p = static_cast<int>(player_choice);
    int c = static_cast<int>(machine_choice);
    if (p - c == 1 || p - c == -2) {
        cout << get_msg(player_choice);
        cout << "Unfortunantly, you win...\n";
    } else {
        cout << get_msg(machine_choice);
        cout << "I WIN, BEEEATCH!!!!\n";
    }
    cout << endl;
}

string get_msg(Choice winner) {
    if (winner == rock)
        return string("Rock smashes scissors, beeatch...");
    else if (winner == paper)
        return string("You know what paper does to rock, COVERAGE!!...");
    else
        return string("CHOP! Scissors cut paper!!....");
}

int rand0toN1(int n) {
    return rand() % n;
}
于 2013-05-29T16:54:58.137 回答