overloading <<

[Micko1]

hi there,

I have an issue when overloading <<.

    string operator << (room * &currentPlayerLocation);
 
 
string room::operator << (room * &currentPlayerLocation)
{
    return roomDescription;
 
}
 

when I call this function:

cout << currentPlayerLocation;

Its cout's the actual memory address - 00346380 instead of the string roomDescription.

What am I doing wrong?

[Ganon11]

From www.cplusplus.com, the function header for the ostream's << operator is:

"ostream& operator<< (ostream& os, const string& str);"

So, to overload it, you need to make a function like:

"ostream& operator<< (ostream&, const yourClass&);"

[Micko1]

From www.cplusplus.com, the function header for the ostream's << operator is:

"ostream& operator<< (ostream& os, const string& str);"

So, to overload it, you need to make a function like:

"ostream& operator<< (ostream&, const yourClass&);"

thankyou for the reply.

so you say to make a function like:

"ostream& operator<< (ostream&, const yourClass&);

would this equate to:

string& operator<<(string&, room const * &currentPlayerLocation);

if so, it doesent work. It puts out error message that it has too many parameters.

[Micko1]

Ive played around with various formats with this method.

Surely there has to be a way

[Ganon11]

No, a string is nothing like an ostream. Your function has to accept an ostream parameter, use that ostream operator to output whatever portions of your class you wish to be seen, and then return that ostream variable. For example, if I had a clock class, my operator<< function might look like:

ostream& operator<<(ostream& out, const clock& myClock) {
   out << myClock.hours << ":" << myClock.minutes << ":" << myClock.seconds;
   return out;
}

Now, when I write

cout << myClock << endl;

what is actually happening is more like this:

operator<<(myClock.operator<<(cout, myClock), endl);

Your operator<< cannot return a string nor expect a string argument if it is to properly overload the << operator.

[weaknessforcats]

Add to Ganon11's comments that since the operator<< must have an ostream& as a first argument, it cannot be a member function. (Recall that member functions have the this pointer as a hidden first argument). Therefore, if your operator<< needs access to class private data, it will need to be a friend function.

[Micko1]

Thankyou both for the reply.

I misunderstood the definition for the overloading teplate, I have made the changes and I'm still getting the memory address.

I think it is because I am using a pointer:

ostream& operator << (ostream &out, const room * &currentPlayerLocation)
{
    out << currentPlayerLocation->roomDescription;
    return out;
}

[Ganon11]

Well, I don't think you need to use a pointer: it can just be

ostream& operator << (ostream &out, const room &currentPlayerLocation);

Also, is roomDescription a private data member? If so, this should be a friend function:

friend ostream& operator << (ostream &out, const room &currentPlayerLocation)

defined in the room header file.

[weaknessforcats]

I think it is because I am using a pointer:

You weren't using a pointer. You were using a reference to a pointer. That's equivalent to using a pointer to a pointer.