C ++ - 从字符串常量到char的不推荐的转换

Question

I don't understand why my compiler is giving me a warning about a deprecated conversion from string to char.

this is where is complaining about the warning:

Just a bit of background of what I'm doing.. I'm trying to understand and practice Exceptions... I'm not sure if its better to just work with char[1000] for the First name and so on.. I will really appreciate if someone help to understand the warning and help me to find a solution.. Thanks..

=================================================================================

class TeLoEnYuco
{
string FN, LN, R;
    double Income;

public:
    const char *getters(){return FN.data(), LN.data(), R.data();}
    virtual char *getFacilityAccess()=0;
    TeLoEnYuco(char *fn, char *ln, char r, double inc)
    {
        if(fn==0) throw Exception(1, "First Name is Null"); //Warning #1
        if(ln==0) throw Exception(2, "Last Name is Null");  //Warning #2
        if(r==0) throw Exception(3, "Rank is Null");        //Warning #3
        if(inc<=0) throw Exception(4, "Income is Null");    //Warning #4

        FN=fn;
        LN=ln;
        R=r;
        Income=inc;
    }
};

=====================Exception class=================================

class Exception
{
    int Code;
    string Mess;

public:
    Exception(int cd, char *mess)
    {
        Code=cd;
        Mess=mess;
    }
    int getCode(){return Code;}
    const char *getMess(){return Mess.data();}
};

Answer 1

I assume Exception 's constructor signature is

Exception(int, char*)

You pass a string literal as a parameter, whose actual type is const char* , but the implicit conversion to char* is legal pre-C++11 (but deprecated, so you get the warning).

Modify the signature to

Exception(int, const char*)

or, better yet,

Exception(int, const std::string&)

To summarize:

char* x       = "stringLiteral";  //legal pre-C++11, deprecated
const char* y = "stringLiteral";  // good
std::string z  ("stringLiteral"); // even better