From -8216216352488438484 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,1ac4d0270ad32ac8 X-Google-Attributes: gidf78e5,public From: Karl Nelson Subject: Re: C++ Strings and NULL Date: 1998/09/29 Message-ID: <6upcf1$kl8$2@mark.ucdavis.edu>#1/1 X-Deja-AN: 395901599 Approved: Fergus Henderson References: <6u9217$cj9$1@mark.ucdavis.edu> <6uj3fq$dm4$1@rocky.jgk.org> X-Original-Date: 29 Sep 1998 01:17:21 GMT Organization: University of California, Davis X-Auth: PGPMoose V1.1 PGP comp.std.c++ iQBFAgUANhCGQ+EDnX0m9pzZAQE7iwF/VLbc2g6Ngwsucx/ZqE7uCNHYmPv7CAEy SrSNG+c7ggn5Xm20XQC6xhalWMjW1z8C =ZQae User-Agent: tin/pre-1.4-980618 (UNIX) (HP-UX/B.10.20 (9000/778)) Newsgroups: comp.std.c++ Siemel Naran wrote: : On 26 Sep 1998 18:15:29 GMT, Joe Keane wrote: :>C string functions don't allow null pointers either, so i don't see why :>people should be surprised by the String class behavior. : Well, you can do "strlen(0)", but you get a segmentation fault : (ie, a program crash). Although I agree with both of these comments, there is some difference between a normal function and a constructor. I expect constructors to be very bullet proof. At least it should throw an exception, but not be left entirely undefined. I do not expect that every "function" in the strings library handle NULL.(or even any function) Because functions are called explicitly by the user it is obvious behavior that it should crash if an unexpected input is applied. It is not obvious (to all users) that (my real) function crashed in the typecasting. At first, I thought that it was the gtk library or the test code I was applying. It took a while to track it back to the constructor in the standard library. : I guess it's for the efficiency. If a func has to do a test : "if (ptr==0) do_something1; else do_something2" you get slighly : worse performance. This is exacerbated by the fact that most : strings are valid -- that is, ptr!=0 is #true -- so having to : test for null explicitly is wasteful. I agree as well. However, constructors are special cases in they may be called without explicit direction to do so. Therefore, they should have higher standards than a regular function. All behavior should be defined for a constructor. : Also, the code looks clumsy when cluttered up with all those 'if' : statements. It would be a total of three if's in inline code, and there is no else involved. current implementation (gcc): basic_string (const charT* s) : dat (nilRep.grab ()) { assign (s); } desired implementation: basic_string (const charT* s) : dat (nilRep.grab ()) { if (s) assign (s); } --Karl --- [ 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 ]