On Tue, Apr 13, 2010 at 14:10, Dirk Hohndel <hohndel at infradead.org> wrote: > +/* the semantic here actually puzzles me: > + ? how can haystack be const char * - yet the return value is char * > + ? after all, it points to a sub-string of haystack... */
Dunno if this is a question from the original source, but the answer if anyone's interested is probably because C doesn't have templates -- you'd ideally like to have it treated as: char *strcasestr(char *haystack, const char *needle); for when you're doing a search and replace on the needle (say), and: const char *strcasestr(const char *haystack, const char *needle); for when you're doing a search for the needle in something you can't modify. But C isn't clever enough to let you say that with just one function (and no fancy #defines), so you have to drop some of the typechecking with the (char*) cast on the return value if you want to handle both use cases, without the compiler complaining about const->non-const conversions in otherwise correct code in one case or the other. Cheers, aj -- Anthony Towns <aj at erisian.com.au>