Xref: utzoo comp.lang.c++:4278 gnu.g++:326
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From: acw%illini@Sun.COM (Alex Wu [GPD] x6-6874)
Newsgroups: comp.lang.c++,gnu.g++
Subject: Re: What's the diff?
Message-ID: <119611@sun.Eng.Sun.COM>
Date: 4 Aug 89 21:34:29 GMT
References: <2731@hsinchu.sw.mcc.com>
Sender: news@sun.Eng.Sun.COM
Lines: 38

In article <2731@hsinchu.sw.mcc.com>, knutson@hsinchu.sw.mcc.com (Jim Knutson) writes:
> What's the difference between the ++ operator overload functions in
> these two examples?  The Lippman book (p. 197) prefers to define the
> function type to return a reference to the class while the Pohl book
> (p. 125) seems to prefer to return the class.  Both seem to work
> equally well as both lvalue and rvalue.
> 
> class counter {
> 	int count;
> public:
> 	counter() { count = 0; }
> 	counter(int c) { count = c; }
> 	counter& operator ++() { count++; return *this; }
> 	value() { return count; }
> };
> 
> class counter {
> 	int count;
> public:
> 	counter() { count = 0; }
> 	counter(int c) { count = c; }
> 	counter operator ++() { count++; return *this; }
> 	value() { return count; }
> };
> 

One difference I can think of is that the first class allows 
the cascade of "++" in this case, that is:

  counter i;
  (i++)++;
  cout << i.value() << '\n'; // gives 2

while the second one gives 1.
Alex Wu 
Sun Microsystems, Inc.
415-336-6874
acw@sun.com