在unordered_map中查找枚舉並獲取其值？

Question

考慮下面的代碼：

enum Keys { 
    Up, 
    Down, 
    Left, 
    Right 
}; 

enum KeyState { 
    Down, 
    Up 
}; 

std::unordered_map<Keys, KeyState> keys; 

keys[Keys::Up] = KeyState::Up; 
keys[Keys::Down] = KeyState::Up; 
keys[Keys::Left] = KeyState::Down; 
keys[Keys::Right] = KeyState::Up; 

我怎麼能寫這樣的方法：

isKeyDown(Keys key) { 
    return true if key has the Up or Down state. 
} 

Answer 1

KeyState value = keys[key]; 
return value == KeyState::Up || value == KeyState::Down; 

當然，這些都是您爲KeyState定義的只有兩個值，所以，因爲它...

return true;