如何正确设置标志

Question

我有一个计时器类，里面有一个标志。当我们没有调用的init（），标记为0后，我们调用的init（），它将我们所说的端部（后置为1），它将被重新设置为0。

class TimerHao 
{ 
private: 
    double seconds; 
    int flag=0; //0: Have not start accumulation. 1: In accumulation, between init() and end(); 

public: 

    void init(); 
    void end(); 
}; 

void TimerHao::init() 
{ 
    if(flag!=0) { throw runtime_error("ERROR!!! Cannot initial the timer before it is ended!"); } 
    ... 
    flag=1; 
} 

void TimerHao::end() 
{ 
    if(flag!=1) { throw runtime_error("ERROR!!! Cannot end the timer before it is initialized!");} 
    ... 
    flag=0; 
} 

我可以通过使用代码：

TimerHao timerhao; 
timerhao.init(); 
... 
timerhao.end(); 
... 
timerhao.init(); 
... 
timerhao.end(); 
... 

我不喜欢标志设置为一个整数，我需要阅读的注释，以了解其含义。实际上，我在我的代码中使用了这种标志，例如标志可以是0,1,2,3,5，每个数字意味着不同的事物。有时候，我对自己的代码感到困惑，我必须仔细阅读注释以了解我在做什么。有没有一种明确的方法来处理这个标志？谢谢。

Answer 1

您可以添加一个枚举，并在代码中使用该值，使代码是不言自明：

class TimerHao 
{ 
private: 

    enum flag_states 
    { 
     FLAG_STATE_NOT_STARTED = 0, 
     FLAG_STATE_IN_ACCUMULATION, 
     // etc 
    }; 

    double seconds; 
    flag_states flag = FLAG_STATE_NOT_STARTED; //0: Have not start accumulation. 1: In accumulation, between init() and end(); 

public: 

    void init(); 
    void end(); 
}; 

void TimerHao::init() 
{ 
    if(flag != FLAG_STATE_NOT_STARTED) { throw runtime_error("ERROR!!! Cannot initial the timer before it is ended!"); } 

    flag = FLAG_STATE_IN_ACCUMULATION; 
} 

void TimerHao::end() 
{ 
    if(flag != FLAG_STATE_IN_ACCUMULATION) { throw runtime_error("ERROR!!! Cannot end the timer before it is initialized!");} 

    flag= FLAG_STATE_NOT_STARTED; 
} 

如果你有机会获得C++ 11，你甚至可以使一个范围的列举和禁止铸造：

class TimerHao 
{ 
private: 

    enum class flag_states 
    { 
     FLAG_STATE_NOT_STARTED = 0, 
     FLAG_STATE_IN_ACCUMULATION, 
     // etc 
    }; 

    double seconds; 
    flag_states flag = flag_states::FLAG_STATE_NOT_STARTED; //0: Have not start accumulation. 1: In accumulation, between init() and end(); 

public: 

    void init(); 
    void end(); 
}; 

void TimerHao::init() 
{ 
    if(flag != flag_states::FLAG_STATE_NOT_STARTED) { throw runtime_error("ERROR!!! Cannot initial the timer before it is ended!"); } 

    flag = flag_states::FLAG_STATE_IN_ACCUMULATION; 
} 

void TimerHao::end() 
{ 
    if(flag != flag_states::FLAG_STATE_IN_ACCUMULATION) { throw runtime_error("ERROR!!! Cannot end the timer before it is initialized!");} 

    flag= flag_states::FLAG_STATE_NOT_STARTED; 
}