From -1458123445469757506 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,5e69b3c02624e7d0 X-Google-Attributes: gidf78e5,public From: sbnaran@uiuc.edu (Siemel B. Naran) Subject: Re: A C++ asymmetry Date: 1999/09/13 Message-ID: #1/1 X-Deja-AN: 524537831 Approved: Fergus Henderson References: X-Original-Date: 12 Sep 1999 19:13:18 GMT X-Complaints-To: news@news.unimelb.edu.au X-Trace: ariel.ucs.unimelb.edu.au 937242968 24680 128.250.37.153 (13 Sep 1999 17:16:08 GMT) Organization: University of Illinois at Urbana-Champaign X-Auth: PGPMoose V1.1 PGP comp.std.c++ iQBFAgUAN90xRuEDnX0m9pzZAQHS+QF9FsOfNQ+EEqd0vsD0xl+FrpOxytGEqSbY MFouSdxQoFHYUSLQEooA22/ajlBHCohE =Hi49 User-Agent: slrn/0.9.5.7 (UNIX) Reply-To: sbnaran@uiuc.edu NNTP-Posting-Date: 13 Sep 1999 17:16:08 GMT Newsgroups: comp.std.c++ On 12 Sep 1999 14:53:59 GMT, Aldo Aleardi wrote: >If I define a default constructor and no copy constructor, the >standard says that a default copy constructor is implicitly defined, >so this code is well-formed >but if I define a default copy constructor and no default constructor >the standard says that a default constructor will not be implicitly >defined, so the following code will not compile: Here is a guess. Most objects need a copy constructor, so one is implicitly defined. The implicit constructor usually does the right thing -- ie, applies the copy constructor for each of the sub-objects. A default constructor should never be implicitly generated, but for backward compatibility with C -- ie, a struct is basically a class with all members public -- the compiler will create one. Example, given "struct S { std::vector v; int i; };" the compiler creates a S::S(). -- -------------- siemel b naran -------------- --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://reality.sgi.com/austern_mti/std-c++/faq.html ]