From: Andre Majorel (amajorel_at_teaser.fr)
Date: 2001-02-26 03:34:42
On 2001-02-22 16:47 +0100, Ullrich von Bassewitz wrote:
>
> On Thu, Feb 22, 2001 at 02:01:57PM +0100, MagerValp wrote:
> > Does the linker link in unused library functions?
>
> No, of course not. So you will only get the additional code if you use it.
Many programs use only a small subset of all the complexity of
printf() and scanf(). If all the format strings are constants,
the compiler may determine which features are used and leave out
those that aren't. It's not particularly easy to do; it requires
printf() and scanf() to be modular.
Alternatively, one may derive (via #ifdef) several versions of
printf()/scanf() and have ld link the most appropriate one.
A significant number of programs use only %s and %d, without any
modifiers.
There is another contingent that uses only %s, %d, %X with
width, precision, justification and padding modifiers ("%-20.20s
%04X %3d").
Suppose that %% and %c should be always supported because
they're so cheap.
Having the compiler parse the format strings may seem incestuous
to some but there are precedents. Certain DOS compilers do it to
decide whether they need to include FP stuff, and GCC to warn if
the fields don't match the arguments.
--
André Majorel <amajorel_at_teaser.fr>
http://www.teaser.fr/~amajorel/
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This archive was generated by hypermail 2.1.3 : 2001-12-14 22:05:39 CET