Re: C89, size_t, and long

Yevgen Muntyan <muntyan.removethis@xxxxxxxx> wrote:

Richard Bos wrote:
Yevgen Muntyan <muntyan.removethis@xxxxxxxx> wrote:

Richard Bos wrote:
Yevgen Muntyan <muntyan.removethis@xxxxxxxx> wrote:

But how is casting size_t to unsigned long more legitimate than

int process_some_data (char *data, unsigned long len);
In this case, you could easily make len a size_t instead.
*If* I can change the code.

If _you_ can't change the code, I would advise not to worry about
whether the ideas expressed in it are legitimate or not; leave that to
the people who did design and do maintain it.

That's good and everything, but doesn't always work on practice
unfortunately. If I happen to use some library which uses long instead
of ssize_t, and if I happen to get a dll of that library, I have a
problem.

(If you use ssize_t at all, you have a problem, because that's not an
ISO type and the idea behind it is broken; the only valid reason to have
it in the first place is covered by ptrdiff_t.)

However, if you use a library and you find you can't trust it, your
options are basically to choose a different library, to roll your own,
or to accept that your supervisor doesn't know what he's talking about
and drink the flavorade. Discussing with yourself whether there's a
theoretical possibility of brokenness when you already know that you
will not be able to stop the breakage is reason to file a defect report
with your managers, not reason to fret about it.

By the way, it seems that some people avoid #includ'ing headers like
stddef.h in library headers due to bugs in C implementations
or for some other obscure reasons. I'd think it adds to this
issue: you can use long for free, it's builtin, but to get
size_t you need an extra header.

Given that size_t is also #defined in <stdio.h>, <stdlib.h> and
<string.h>, probably the three most #included headers, without which I
can hardly imagine a useful ISO C program of any reasonable size, as
well as in <time.h> and <wchar.h>, IMO people who do this should do a
reality check.

Perhaps. Or maybe it's because many vendors put lot of non-standard
stuff into standard headers. Say, if you #include <string.h> and
do not #define _GNU_SOURCE with glibc, then you don't get strndup()
declaration.

So? What does that have to do with the price of fish?

You need functions from <string.h>, you #include <string.h>, and you get
size_t for free. Ditto with <stdio.h>, and all the others. If you choose
not to #include a header you should #include because you just _might_
one day have to deal with Ganuck, the difference between unsigned long
and size_t is the least of your problems; getting a grip on your
priorities is much more important.

Richard
.

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