Re: [Sheflug] c++ & mem

["Stephen J. Turnbull" <nospam [at] sk.tsukuba.ac.jp>]

>>>>> "Al" == Alex Hudson <home [at] alexhudson.com> writes:

    Al> Old code, yes, efficient code? I don't think I necessarily
    Al> agree with that.  Efficient, maybe, if the coder is a C coder
    Al> who doesn't do so much C++. C++ overall is generally much
    Al> nicer to streamline than C code.

By "efficient code" I meant things like unrolling loops by hand
(Duff's device -- a compiler can _never_ get that right because
compilers don't read hardware data sheets), short-circuiting the
virtual function call mechanism when you know which type you're going
to have, defining multiple hand-tweaked versions of linked lists
rather than deriving from a single "class link { link *next; union {
void *object; anything_small_enough_to_fit_in_a_void*'s_storage
thing;};}" (or better using something from a standard class library)
and such-like.  No-nos in well-styled C++.  Some of these can be
handled efficiently with C++ features (eg, the class link can often
avoid a level of indirection with a template), but that may or may not
increase clarity.)

    Al> No, I disagree completely. If you're planning on programming
    Al> in C++, you need to test the compiler *with* C++, not C - that
    Al> means the libraries, etc.

You need to reread chapter one of K&R again, I see.

Case in point: the original poster did not need to use libstdc++ to
run into problems.  And the kind of problems he had are typically
harder to solve by email than actual language issues; eg, no DOS
person would ever have figured out the actual problem since DOS always
includes . in %PATH.

OTOH, if he'd written the program using iostreams, a lot of the advice
would have focused on getting that library working, right?

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