What is the other way of calling the overloaded assignment operator?

nowocien · #1 02-Jul-2009, 16:03

in the code below.. what is the other way of calling the overloaded assignment operator? descriped in the commnets below. Also, this function returns a reference "&", this mean the copy constructor is called, correct?

CPP / C++ / C Code:

IntlPhoneNumberWS& IntlPhoneNumberWS::operator=(const IntlPhoneNumberWS& s){
   IntlPhoneNumber::operator=(s); //(IntlPhoneNumber&)operator=(s); not sure if this would work??
   if (this != &s){               //(IntlPhoneNumber&)(*this).operator=(s); or this, not sure??
      if (subscriber != NULL) delete [] subscriber;
      if (s.subscriber != NULL){
	 subscriber = new char[strlen(s.subscriber) + 1];
	 strcpy(subscriber, s.subscriber);
      }else subscriber = NULL;
   }
   return *this;
}

Thanks
Daniel

ocicat · #2 02-Jul-2009, 23:03

Quote:

Originally Posted by nowocien

in the code below.. what is the other way of calling the overloaded assignment operator?

Quote:

//(IntlPhoneNumber&)(*this).operator=(s); or this, not sure??

If you are not sure, write a simple example to test your hypothesis.

Member functions (not static member functions...) require an object to call the member function. While the following:

Quote:

(*this).operator=(s);

...does take an object & calls a member function, why dereference this followed by using the dot (.) operator? Why not use -> as in the following:

Code:

this->operator=(s);

Writing simple test cases yourself can help you:

learn the syntax.
think about the consequences of the syntax at a deeper level.
will help you teach yourself without having to wait for someone else to do it for you.

Quote:

Also, this function returns a reference "&", this mean the copy constructor is called, correct?

No, not necessarily. The ampersand allows an object to be used as an lvalue (left-hand side of an assignment...) or rvalue (right-hand side of an assignment...). A copy constructor may be called in some instances, but this isn't a direct result of the signature of assignment operator overload as it is a consequence that an object is being initialized with the value of another object.

nowocien · #3 03-Jul-2009, 11:39

ok thanks OCICAT, yeah the thing is i test so much stuff that some times its just easier to post a question and go back to it later, the responses on the forum are so fast that I got spoiled. I love this place. Yeah i know -> is better then (*this).operator but im just a begginer so I want to make sure I know all the possiblilites, other people have different style, i want to understand everything

Thanks AGain, this forum is the shittt!!

nowocien · #4 06-Jul-2009, 13:23

Just wanted to add, for those that may be learning like me that:

Quote:

Also, this function returns a reference "&", this mean the copy constructor is called, correct?

the copy constructor is call when returning BY VALUE, passing BY VALUE to a function as a paramater and initialization of an object using the assigment '=' operator to another object as OSICAT pointed out.

Thanks
Daniel

CPlus2Progammer · #5 04-Sep-2009, 10:03

in your code above i see you return an object on the free store (heap) "By Reference" or easy to say an "Alias" of Object on the free store (heap).

return *this; // right ? its mean you dereference the this pointer of current object its pointed to, an the result is the object on the free store (heap), not a copy constructor or constructor anymore.

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What is the other way of calling the overloaded assignment operator?

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