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Re: [PATCH] manual: Document %m instead of %a for formatted input.


On Tue, Feb 11, 2014 at 09:32:49AM -0800, Roland McGrath wrote:
> > 	* manual/stdio.texi (Dynamic String Input): Recommend %m modifier instead of %a.
> 
> This line is too long.
> 
> > +A POSIX.1-2008 extension to formatted input lets you safely
> 
> It doesn't make sense to talk about "a POSIX.1-2008 extension", even if
> that were accurate.  (Actually it's an ISO C-1990 feature.)  Something in
> one of the core standards we implement is not "an extension".  The manual
> also needs to continue to document the GNU %a extension, and explain the
> effect of -std mode.  %a is also mentioned in @node String Input Conversions
> that needs to be updated too.

Here. As original author thinks its enough it would be better add -std
and differences in separate commit.

	* manual/stdio.texi (Dynamic String Input): Recommend %m modifier
	instead of %a.
	(String Input Conversions): Document m modifier.

diff --git a/manual/stdio.texi b/manual/stdio.texi
index 1161a9a..bec7052 100644
--- a/manual/stdio.texi
+++ b/manual/stdio.texi
@@ -3536,6 +3536,10 @@ successful assignments.
 @cindex flag character (@code{scanf})
 
 @item
+An optional flag character @samp{m} (valid with string conversions only)
+which requests allocation of a buffer long enough to store the string in.
+
+@item
 An optional flag character @samp{a} (valid with string conversions only)
 which requests allocation of a buffer long enough to store the string in.
 (This is a GNU extension.)
@@ -3929,18 +3933,21 @@ input with a comprehensible error message, not with a crash.
 @node Dynamic String Input
 @subsection Dynamically Allocating String Conversions
 
-A GNU extension to formatted input lets you safely read a string with no
-maximum size.  Using this feature, you don't supply a buffer; instead,
-@code{scanf} allocates a buffer big enough to hold the data and gives
-you its address.  To use this feature, write @samp{a} as a flag
-character, as in @samp{%as} or @samp{%a[0-9a-z]}.
+Since ISO C-1990 there is feature to safely read a string with no maximum 
+size.  Using this feature, you don't supply a buffer; instead, @code{scanf}
+allocates a buffer big enough to hold the data and gives you its address.
+To use this feature, write @samp{m} as a flag character, as in 
+@samp{%ms}, @samp{%m10c} or @samp{%m[0-9a-z]}.
+
+There is also a GNU extension @samp{a} modifier that works similar
+functionality.
 
 The pointer argument you supply for where to store the input should have
 type @code{char **}.  The @code{scanf} function allocates a buffer and
 stores its address in the word that the argument points to.  You should
 free the buffer with @code{free} when you no longer need it.
 
-Here is an example of using the @samp{a} flag with the @samp{%[@dots{}]}
+Here is an example of using the @samp{m} flag with the @samp{%[@dots{}]}
 conversion specification to read a ``variable assignment'' of the form
 @samp{@var{variable} = @var{value}}.
 
@@ -3948,7 +3955,7 @@ conversion specification to read a ``variable assignment'' of the form
 @{
   char *variable, *value;
 
-  if (2 > scanf ("%a[a-zA-Z0-9] = %a[^\n]\n",
+  if (2 > scanf ("%m[a-zA-Z0-9] = %m[^\n]\n",
 		 &variable, &value))
     @{
       invalid_input_error ();


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