我似乎無法獲得Visual C++ Express（2010）識別枚舉類

Question

嗨，大家好（和女孩）， 我正在努力重新熟悉C++後，只使用Python太久。我已經用MS Visual C++ 2010 Express版編寫了一個小程序，並且我已經遍地查找了爲什麼編譯器似乎不喜歡使用enum類Choice的罪魁禍首。編譯器抱怨這個名字的命名空間不存在。現在，我應該說我寫的所有以前的C/C++代碼都在學術環境中，因此我使用了完整的IDE。無論如何，我附上下面的代碼，請原諒我，如果這是不正確的方法發佈它。如果是這樣，請參考我的正確方法，我將在今後使用它。提前感謝您提供任何幫助或洞見任何人可能能夠借出。代碼如下。

#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; 
} 

再次感謝您花時間幫助我。我似乎記得經常使用C++來聲明類，並且不知道爲什麼它不會識別它。再次感謝您抽出時間。法院（南卡羅來納州克萊姆森大學）

Answer 1

VC++在2010年不支持枚舉類。您需要2012。

Answer 2

enum class在visual C++ 2010中不受支持，但我認爲它在vC++ 2012中。 請參閱here。

你將不得不升級你的編譯器或者使用普通的「enum」，當然它的工作原理略有不同。

Answer 3

所以它看起來像你想使用名稱空間「選擇」，但你沒有先定義它。 要定義一個新的命名空間，定義它像：

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

但事實上，我不知道你需要定義任何命名空間... 在你的情況，我找出的問題是，你聲明「枚舉類選擇「，而不僅僅是」枚舉選擇「。請C++例如讀取有關枚舉使用此鏈接：http://www.cplusplus.com/forum/beginner/44859/

我修改你的代碼這種方式，它運行良好：

#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; 
} 

Answer 4

枚舉類是介紹爲C++ 11標準的一部分。它不會存在於VC2010中。 您需要升級到VC2012才能使用此功能。否則，從枚舉聲明中刪除「class」。

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.