Gavin Lambert wrote: > At 13:05 24/09/2009, Jim Idle wrote: >>Some platforms define this to be undefined though. Remember there >>are lots if embedded systems that use this. Hence the qualification. >>I think it would have been better to define free(NULL) as safe >>myself but early Lib C would crash if you did this and I think it >>was C++ that first took a stand? > > I haven't looked at the standards recently, but from what I recall > "delete NULL;" is guaranteed safe but "free(NULL);" wasn't.
C89 clause 4.10.3.2: # The free function causes the space pointed to by ptr to be # deallocated, that is, made available for further allocation. # If ptr is a null pointer, no action occurs. [...] (This is the same in C89 and C99; in the latter it is clause 7.20.3.2.) > I definitely recall seeing some static testers and malloc replacements > (some for performance, some for allocation debugging) that reacted badly > to use of "free(NULL);" (sometimes just a failed assertion, sometimes > worse). That would be a bug. C89 is 20 years old; there's really no excuse for writers of testers and malloc replacements not to have read the sections of it that directly apply to them. -- David-Sarah Hopwood ⚥ http://davidsarah.livejournal.com List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to il-antlr-interest@googlegroups.com To unsubscribe from this group, send email to il-antlr-interest+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en -~----------~----~----~----~------~----~------~--~---
