From 1333310988144331606 X-Google-Thread: f78e5,3c316a202087bfac X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!news.glorb.com!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsfeed.vmunix.org!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!stump.algebra.com!devnull From: aon.912719634@aon.at (Nicolas Pavlidis) Newsgroups: comp.std.c++ Subject: Re: Defining undefined, etc., behavior Date: Tue, 18 Apr 2006 16:57:31 GMT Lines: 118 Sender: mail2news@demon.net Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <4444e14a$0$3888$91cee783@newsreader01.highway.telekom.at> References: <123m587c3abqge4@corp.supernews.com> <4442b95c$0$12939$91cee783@newsreader02.highway.telekom.at> <4ah3ofFt9979U1@individual.net> NNTP-Posting-Host: news.news.demon.net Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: news.demon.co.uk 1145379459 14026 158.152.254.254 (18 Apr 2006 16:57:39 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Tue, 18 Apr 2006 16:57:39 +0000 (UTC) X-Original-To: std-c++@mailman.ucar.edu X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-User-Agent: Thunderbird 1.5 (Windows/20051201) X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id k3IGvVcU025648; Wed, 19 Apr 2006 02:57:31 +1000 (EST) X-Path: comp-std-cpp-robomod!not-for-mail X-Delivered-To: std-c++@ucar.edu X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Newsgroups: comp.std.c++ Xref: g2news1.google.com comp.std.c++:1594 Bo Persson wrote: > "Nicolas Pavlidis" skrev i meddelandet > news:4442b95c$0$12939$91cee783@newsreader02.highway.telekom.at... >> Hi! >> >> Again a disclaimer: I'm far away from beeing an expert, but I whant >> to >> take this thread to note some things, which seem anoying to me. >> >> NULL@NULL.NULL wrote: >>> Scott Meyers posted: >>> >>>> What work has been done on eliminating undefined behavior in C or >>>> C++? >>>> Off the top of my head, some undefined behavior is due to "stupid >>>> user >>>> behavior," e.g., indexing beyond the end of an array, >>>> dereferencing a >>>> null pointer, etc. >>> >>> I agree. Stuff like the following is just "stupid": >>> >>> int *p; >>> >>> *p = 5; //Undefined Behaviour >>> >> This is one thing, and in that case its really stupid, but, the same >> behaviour can happen across longer code, with some function - calls >> inside, AFAIK this code is also undefined: >> >> int my_int; // missing initialisation >> cout << my_int << endl; >> >> Why is it impossible to let the compiler do the initialisation for >> me, I >> have to do it anyway, either in my code, where I can leave it otu, >> or, >> on the secure side, the compiler does tyhis thing for me. > > Some compilers do warn you if you use uninitialized variables. That is > fine. That is what I mean. Why not all? If I like to use uninitialized variables, I can use them and I'm able to ignore or even supress the warning. But if I don't like them, but write code that uses them I've the opportunity to get reid of them in my code, and yes, I don't liek them :-). > One expert argument against having the compiler "fix" broken code, is > that the code is old C-style anyway. In C++ the rule was changed, so > you generally can delay the declaration of the variable until you have > its initial value available. That solves the problem. I don't thik so :-). Not only old C - COde is affected by these problems, also "new" C++ - code is affected, because it just hapen, if you want or not, either if you are lazy or if you just miss one stupid initialisazion :-(. > Also, in non-broken code, zero initializing all variables at the point > of declaration and then assigning them later, would make the old C > code run slower when compiled as C++. Not the best marketing trick! Sorry, in any case I have to write somehting before I read it or not? And the biggest Problems ar not the loop - counters for for - loops. What I mean are struct - mebers for example, why I'm forced to do the inistalisazion for private - members to zero (in case of an int)? >> Even if I do that, I can run into problems, think of >> std::list::front. >> If the list is empyt everythign can happen, again the question, why >> not >> pakking the code into the method. Why should the user must care >> about >> the inetrnal state of the list, ind this example. > > Why should the programmer be bothered with the correctness of his > program? :-) Why not :-)? > >> he typemixing is another problem, that is solved by specific >> compilers, >> they warn you at least, why not forbis some things, you all have >> called >> stupid,if they are soo stupid? > > This is all part of the C inheritance. The combined blessing and curse > of C++. :-) > There are several other languages designed to avoid these problems. > Can you name one? Why not? Were they not successful? Which type of language to you mean? As powerful as C++ or some other language? :-). Best regards, Nicolas P.S. Yes I like C++ :-) -- | Nicolas Pavlidis | Elvis Presly: | | Student of SE & KM | "Into the goto" | | pavnic@sbox.tugraz.at | ICQ #320057056 | | ------------University of Technology, Graz----------------- --- [ 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://www.comeaucomputing.com/csc/faq.html ]