c++ - C++ 中的枚举具有原始值？

Question

是否可以为 C++ 中的枚举提供原始值？

Swift 示例:

enum AnOperations: String {
    case Addition = "+"
    case Subtraction = "-"
    case Division = "/"
}

// if or switch
if AnOperations.Addition.rawValue == "+" {
    print("true")
}

Answer 1

我必须承认，除了它的名字之外，我对 Swift 一无所知。

在 C++ 中，枚举中不能使用字符串。

<强> Enumeration Declaration :

An enumeration is a distinct type whose value is restricted to a range of values (see below for details), which may include several explicitly named constants ("enumerators"). The values of the constants are values of an integral type known as the underlying type of the enumeration.

(强调我的。)

什么可能有效:

enum AnOperations: char {
  Addition = '+',
  Subtraction = '-',
  Division = '/'
};

因为 char 是整数类型之一。

示例:

#include <iostream>
#include <sstream>

int main()
{
  enum AnOperations: char {
    Addition = '+',
    Subtraction = '-',
    Division = '/'
  };
  std::string text = "1 + 2";
  std::istringstream in(text);
  int arg1, arg2, result; char op;
  in >> arg1 >> op >> arg2;
  switch (op) {
    case Addition: result = arg1 + arg2; break;
    case Subtraction: result = arg1 - arg2; break;
    case Division: result = arg1 / arg2; break;
    default:
      std::cerr << "Unknown op. '" << op << "'!\n";
      return 1;
  }
  std::cout << arg1 << ' ' << op << ' ' << arg2 << " = " << result << '\n';
  return 0;
}

输出:

1 + 2 = 3

Live Demo on coliru