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printf extension doc bug
- To: libc-alpha at sources dot redhat dot com
- Subject: printf extension doc bug
- From: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
- Date: Tue, 10 Oct 2000 22:03:22 +0100 (BST)
The documentation for glibc's feature for customising printf formats is
self-contradictory: it gives an example of %z, but says that lengths
(which now include z) cannot be used as conversions. This patch changes
the example and adds a warning about using lowercase letters.
--- stdio.texi.orig Fri Apr 21 22:11:30 2000
+++ stdio.texi Tue Oct 10 20:59:43 2000
@@ -2098,11 +2098,13 @@
@comment GNU
@deftypefun int register_printf_function (int @var{spec}, printf_function @var{handler-function}, printf_arginfo_function @var{arginfo-function})
This function defines the conversion specifier character @var{spec}.
-Thus, if @var{spec} is @code{'z'}, it defines the conversion @samp{%z}.
+Thus, if @var{spec} is @code{'Y'}, it defines the conversion @samp{%Y}.
You can redefine the built-in conversions like @samp{%s}, but flag
characters like @samp{#} and type modifiers like @samp{l} can never be
used as conversions; calling @code{register_printf_function} for those
-characters has no effect.
+characters has no effect. It is advisable not to use lowercase letters,
+since the ISO C standard warns that additional lowercase letters may be
+standardized in future editions of the standard.
The @var{handler-function} is the function called by @code{printf} and
friends when this conversion appears in a template string.
--
Joseph S. Myers
jsm28@cam.ac.uk