Re: Overload Operators for referenced objects?

From:

Kai-Uwe Bux <jkherciueh@gmx.net>

Newsgroups:

comp.lang.c++

Date:

Sun, 11 Feb 2007 13:36:28 -0500

Message-ID:

<eqnnnc$gi7$1@murdoch.acc.Virginia.EDU>

Jonas Huckestein wrote:

hello,

somehow i can't figure out, how to overload the [] operator for a
referenced object. if i have

class MyClass {

int operator[](int i) { return 1; };

You might want to consider using std::size_t instead of int as the argument
type.

};

...

MyClass* oskar = new MyClass();
cout << oskar[3];

Two options:

oskar->operator[](3)

or (more readable):

(*oskar)[3]

delete oskar;

the compiler says "cannot convert ?OperatorSequence? to ?int? in
initialization". with

MyClass oskar;

it works, though. how can i use the overloaded [] for pointers? i also
need to overload arithmetic operations in my class, is there a similar
problem when dealing with referenced objects?

The problem is that you don't distinguish between the pointer and the
pointee. If you want to add the pointees, you have to get them first by
dereferencing the pointer. The problem is totally unrelated to your class,
you would face it with pointers of type int* just as well.

int* ap = new int ( 5 );
int* bp = new int ( 6 ); // warning: already possibly leaking ap.
ap + bp; // bogus: trying to add two pointers
*ap + *bp; // ok: adding pointees.
delete ap;
delete bp;

Best

Kai-Uwe Bux