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Diffstat (limited to 'manual/stdio.texi')
| -rw-r--r-- | manual/stdio.texi | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/manual/stdio.texi b/manual/stdio.texi index 4c90b25447..fbf218ebf3 100644 --- a/manual/stdio.texi +++ b/manual/stdio.texi @@ -895,7 +895,7 @@ The conversion specifications in a @code{printf} template string have the general form: @example -% @var{flags} @var{width} @r{[} . @var{precision} @r{]} @var{type} @var{conversion} +% @r{[} @var{param-no} @r{$]} @var{flags} @var{width} @r{[} . @var{precision} @r{]} @var{type} @var{conversion} @end example For example, in the conversion specifier @samp{%-10.8ld}, the @samp{-} @@ -910,6 +910,33 @@ initial @samp{%} character followed in sequence by: @itemize @bullet @item +An optional specification of the parameter used for this format. +Normally the parameters to the @code{printf} function a assigned to the +formats in the order of appearence in the format string. But in some +situations (such as message translation) this is not desirable and this +extension allows to specify and explicit parameter to be used. + +The @var{param-no} part of the format must be an integer in the range of +1 to the maximum number of arguments present to the function call. Some +implementations limit this number to a certainly upper bound. The exact +limit can be retrieved by the following constant. + +@defvr Macro NL_ARGMAX +The value of @code{ARGMAX} is the maximum value allowed for the +specification of an positional parameter in a @code{printf} call. The +actual value in effect at runtime can be retrieved by using +@code{sysconf} using the @code{_SC_NL_ARGMAX} parameter @pxref{Sysconf +Definition}. + +Some system have a quite low limit such as @math{9} for @w{System V} +systems. The GNU C library has no real limit. +@end defvr + +If any of the formats has a specification for the parameter position all +of them in the format string shall have one. Otherwise the behaviour is +undefined. + +@item Zero or more @dfn{flag characters} that modify the normal behavior of the conversion specification. @cindex flag character (@code{printf}) |