C++异常重载构造函数

Question

我尝试创建自己的异常，我可以使用一个或两个参数抛出该异常。所以我所做的就是重载异常的构造函数。然而，第二个构造函数似乎没有被调用。这是我的代码:

code-listing-1.

class myException: public std::exception {
public:
    /*
     * first constructor
     */
    myException(unsigned short ExceptionCode):exception(){
        code = ExceptionCode;
        errorMessage = std::string("");
    }
    /*
     * second constructor
     */
    myException(unsigned short ExceptionCode, std::string errorMessage):exception(){
        std::cout << "debugging message";//present here for debugging purpose only
        code = ExceptionCode;
        this->errorMessage = errorMessage;
    }

    const char * what() const throw ()
    {   
        std::string tmp;
        switch(code){
            case MYERROR_CODE_1:
                tmp = std::string("MYERROR_CODE_1 : ");
                if(errorMessage.empty())
                    tmp += std::string("this is a default error message for code 1");
                tmp += errorMessage;
                break;
            case MYERROR_CODE_2:
                tmp = std::string("MYERROR_CODE_2 : ");
                if(errorMessage.empty())
                    tmp += std::string("this is a default error message for code 2");
                tmp += errorMessage;
        }


      return tmp.c_str();
    }
    ~myException() throw(){}

private:
    std::string errorMessage;
    unsigned short   code;
};

例如，当我这样调用它时:

code-listing-2.

void myFunction(myClass myObject){
    //some code
    if(conditionsMeet)
         throw myException(MYERROR_CODE_2,"this is a more specific custom message for code 2");
    //some other code
}

“调试消息”根本没有出现。当我评论“第一个构造函数”时，我得到一个错误和很多警告。

error-listing-1.

main.cpp:28:41: error: no matching function for call to 'myException::myException(ExceptionCode)'
     throw myException(MYERROR_CODE_2);
                                         ^
main.cpp:28:41: note: candidates are:
In file included from Node.h:12:0,
                 from main.cpp:10:
myException.h:50:5: note: myException::myException(short unsigned int, std::string)
     myException(unsigned short ExceptionCode, std::string errorMessage):exception(){
     ^
myException.h:50:5: note:   candidate expects 2 arguments, 1 provided
myException.h:44:7: note: myException::myException(const myException&)
 class myException: public std::exception {
       ^
myException.h:44:7: note:   no known conversion for argument 1 from 'ExceptionCode' to 'const myException&'

编辑:错误代码定义如下:

代码 list 2。

enum ExceptionCode{
    MYERROR_CODE_1                 = 1,
    MYERROR_CODE_2                 = 2,
};

谁能向我解释我做错了什么以及为什么？提前致谢。

Answer 1

正如 Massa 所指出的，您得到的编译错误不会因为您的示例行而引发:

throw myException(MYERROR_CODE_2,"this is a more specific custom message for code 2");

而是因为您在代码的其他地方调用了第一个构造函数，例如:

throw myException(MYERROR_CODE_2);