On Sunday 24 May 2026 22:38:16 (+02:00), mickmackusa wrote:
> Hi all, may I request that the documentation pages for sscanf() and
> fscanf() be reviewed?
Thank you for the detailed documentation on SO and invoking some
initiative here on the list.
> I have been doing a fair amount of Google searching, but either my
keywords
> are not ideal or there really is no mention of this floating around
(even
> the C++ pages that I read don't mention it).
C++ might be a red herring, sscanf is more ANSI C and for PHP the
original code from TCL8.3.0:
<https://www.tcl-lang.org/software/tcltk/relnotes/tcl8.3.0.txt>
"The main site for Tcl/Tk source distributions is SourceForge" [1],
that version's sources and manual:
* tcl8.3.0.tar.gz -- 2001-07-30 2.5 MB
* tcl8.3.0.html.tar.gz -- 2001-07-30 582.1 kB
<https://sourceforge.net/projects/tcl/files/Tcl/8.3.0/*>
For sscanf ANSI C I have found
The Unix Heritage Society <https://www.tuhs.org>
an invaluable resource to learn about ANSI draft interpretations as
they have archives of Usenet comp.std.c in indexable hypertext
documents as well as gzipped tarballs:
<https://www.tuhs.org/Usenet/comp.std.c/>
I found it helpful in context of PHP to understand the communication
in the user's network (Usenet/USENIX network) with the Unix-to-Unix
Copy Protocol (UUCP) and also the nomenclature of C and other
computer lanugages standardization processes.
To give an example for questions like why the PHP implementation of
fscanf() might be reading one line at a time as you briefly mentioned
off-list IIRC, I found a message 'Hints for using "scanf"' [2] that
helped me to reflect such kind of thoughts.
Let me illustrate with an excerpt of the exemplary message written
by Martin Weitzel in January 1990:
> If you want to analyze interactive (or unpredictable) input,
> my advice is to read a complete line with "fgets" (avoid "gets"!!)
> or read up to some other significant token with "gets/fgets".
> After that, use "sscanf" on the buffer you just read.
In our sources we can find the following lines:
buf = php_stream_get_line((php_stream *) what, NULL, 0, &len);
if (buf == NULL) {
RETURN_FALSE;
}
result = php_sscanf_internal(buf, format, argc, args, 0,
return_value);
This is PHP's way of fgets() followed by sscanf() on the buffer,
as illustrated by M. Weitzel back in 1990.
As you requested, I illustrative now "reviewed" the manual page for
the fscanf() function [3] in this regard:
> Each call to fscanf() reads one line from the file.
Find out more about networked computing not only in
comp.infosystems.www.authoring.cgi (check June 8 '95) but also
in the comp.* hierarchy when you want to research in the archives.
best
-- hakre
p.s. I took some time yesterday to document an example listing
of how to make use of the "underflow behavior", e.g. for testing
in GH-19088 [4] in case of interest.
[1]: https://www.tcl-lang.org/software/tcltk/download.html
[2]: https://www.tuhs.org/Usenet/comp.std.c/1990-January/000290.html
[3]: https://web.archive.org/web/20170812235246/http://php.net/fscanf
[4]: https://github.com/php/php-src/issues/19088#issuecomment-4534153067
