Question

I am having difficulty writing my code in the way it should be written. This is my default constructor:

Address::Address() : m_city(NULL), m_street(NULL), m_buildingNumber(0), m_apartmentNumber(0)
{}

…and this is my other constructor:

Address::Address(const char* city, const char* street, const int buildingNumber,const int apartmentNumber) : m_city(NULL), m_street(NULL)
{
    SetAddress(city,street,buildingNumber,apartmentNumber);
}

I have to initialize my city and street fields as they contain char * and my setter uses remove to set a new city for example. I would very much like to hear your opinion on how to write it in the right way without repeating code.
this is my SetAddress code :

bool Address::SetAddress(const char* city, const char* street, const int buildingNumber, const int apartmentNumber)
{
    if (SetCity(city) == false || SetStreet(street) == false || SetBuildingNumber(buildingNumber) == false || SetApartmentNumber(apartmentNumber) == false)
        return false;
    return true;
}

and this is my SetCity:

bool Address::SetCity(const char* city)
{
    if(city == NULL)
        return false;
    delete[] m_city;
    m_city = new char[strlen(city)+1];
    strcpy(m_city, city);
    return true;
}

1 more question if i do change char* to string how can i check if string city doesnt equal to NULL as i know string does not have the “==” operator and string is an object and cannot be equal to null,
how can i check if the string i get is indeed legeal.

Answer 1

You can combine the two ctors:

Address::Address(const char* city=NULL, 
                 const char* street=NULL, 
                 int buildingNumber=0,
                 int apartmentNumber=0) 
: m_city(city), 
  m_street(street), 
  m_buildingNumber(buildingNumber), 
  m_apartmentNumber(apartmentNumber)
 {}

[The top-level const on buildingNumber and apartmentNumber accomplished nothing and attempt to move implementation information into the interface, so I remove them.]

Of, if you really prefer:

Address::Address(const char* city=NULL, 
                 const char* street=NULL, 
                 int buildingNumber=0,
                 int apartmentNumber=0) 
{
    SetAddress(city,street,buildingNumber,apartmentNumber);
}

I generally prefer the former, but if SetAddress qualifies its inputs, it may be worthwhile. Of course, the suggestion to use std::string instead of pointers to char is a good one as well, but that’s a more or less separate subject.

One other minor note: this does differ in one fundamental way from your original code. Your code required either 0 or 4 arguments to the ctor. This will accept anywhere from 0 to 4, arguments so a person could specify (for example) a city and street, but not a building number or apartment number. If it’s really important to you that attempts at using 1, 2 or 3 arguments be rejected, this approach won’t be useful to you. In this case, the extra flexibility looks like an improvement to me though — for example, if somebody lives in a single-family dwelling, it’s quite reasonable to omit an apartment number.