Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!midway!mimsy!panache.cs.umd.edu!davew
From: davew@panache.cs.umd.edu (David G. Wonnacott)
Newsgroups: comp.lang.c++
Subject: Re: Question about C++
Message-ID: <32853@mimsy.umd.edu>
Date: 12 Apr 91 15:52:54 GMT
References: <1991Apr11.181205.22641@mintaka.lcs.mit.edu>
Sender: news@mimsy.umd.edu
Reply-To: davew@panache.cs.umd.edu (David G. Wonnacott)
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 45

In article <1991Apr11.181205.22641@mintaka.lcs.mit.edu> rjc@geech.gnu.ai.mit.edu (Ray Cromwell) writes:
>
> For instance in Complex.h you see member functiuons declared as:
>   Complex& Complex(double re, double im);
>         ^^

Actually, I don't see anything like that in Complex.h.  It looks like
you have a complex constructor with a return type, which is illegal
(at least in AT&T C++ -- and I checked the g++ headers on my system
and they show no such thing).  If you have been declaring return types
for constructor functions, you should look again at the section on
constructors in your favorite C++ book.

In any case, the question about return type declarations makes sense
for functions other than constructors and destructors, so, taking the
liberty of re-nameing your function make_complex,

>  Is this just a new formatting style encouraged in C++ or a new
>use of the & operator. Why not write:  
>   Complex &make_complex(double re, double im);

These two declarations are equivalent, much as "char* p" and "char *p"
are the same.  The choice is a matter of style.  Some people like the
first to show that the "*" is part of the type information, not the
identifier.  Others prefer the second because it extends better to
multi-pointer declarations like "char *p, *q".

>  Or
>   Complex *make_complex(double re, double im);

This, on the other hand, is quite different.  It returns a pointer,
not a reference, so you have to explicitly follow the pointer (using
unary * or ->) returned by the function.  For example, you would write

	i = *make_complex(0, 1); /* funciton returns pointer */

instead of

	i = make_complex(4, 5);  /* function returns reference or value */

--
David Wonnacott
davew@tove.cs.umd.edu

     Although the moon is smaller than the earth, it is further away.