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| From | Eric Sosman <esosman@ieee-dot-org.invalid> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: scanf() |
| Date | 2012-08-07 15:03 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <jvropp$8tl$1@dont-email.me> (permalink) |
| References | <jvpb53$bo5$1@speranza.aioe.org> <0.8672b74d90d99a7ba880.20120806224900BST.87r4rjzo6r.fsf@bsb.me.uk> <jvrn8u$2df$1@speranza.aioe.org> |
On 8/7/2012 2:37 PM, Edward Rutherford wrote:
> Ben Bacarisse wrote:
>
>> Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> writes:
>>
>>> If scanf() fails for a matching error, [...] Could it
>>> have read on through an indeterminate amount of stdin, [...]
>>
>> No, it can read an unlimited number of characters before reporting a
>> matching failure. [...]
>
> That's unfortunate, because then there's no way to recover the non-
> matching data, as far as I can see.
Right. That's one of the reasons scanf() and its brethren
are difficult to use in "industrial-strength" applications.
> Wouldn't it be better if scanf() buffered non-matching characters, either
> seemlessly in the background (so that future reads from stdin saw those
> characters) or by returning a pointer to a buffer containing them?
Which part of "indeterminate amount" and "unlimited number"
do you have trouble understanding? ;-)
If you need to revisit those characters, you'll need to buffer
them yourself (or fseek() back to them, if the input is seekable).
You'd need to read them into a buffer first, and then apply sscanf()
to the buffer; as Ben suggests, the "%n" specifier may be helpful
in navigating.
My own preference when parsing input fancy enough to warrant
backtracking is to read it as plain characters (perhaps a line at
a time, if "line" makes sense), store them in a buffer, and pick
them apart with strxxx() functions. Even sscanf() has infelicities.
--
Eric Sosman
esosman@ieee-dot-org.invalid
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scanf() Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2012-08-06 20:58 +0000
Re: scanf() Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-06 17:29 -0400
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-06 14:40 -0700
Re: scanf() James Kuyper <jameskuyper@verizon.net> - 2012-08-06 17:39 -0400
Re: scanf() Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-06 22:49 +0100
Re: scanf() Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2012-08-07 18:37 +0000
Re: scanf() James Kuyper <jameskuyper@verizon.net> - 2012-08-07 15:01 -0400
Re: scanf() Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-07 15:03 -0400
Re: scanf() Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-07 20:51 +0100
Re: scanf() John Bode <jfbode1029@gmail.com> - 2012-08-09 14:00 -0700
Re: scanf() Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-11 03:08 -0700
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-11 10:40 -0700
Re: scanf() Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-11 13:34 -0700
Re: scanf() "BartC" <bc@freeuk.com> - 2012-08-11 23:04 +0100
Re: scanf() James Kuyper <jameskuyper@verizon.net> - 2012-08-11 19:20 -0400
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-11 17:30 -0700
Re: scanf() Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-11 20:41 -0400
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-11 18:13 -0700
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-11 18:16 -0700
Re: scanf() Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-11 21:32 -0400
Re: scanf() Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-12 04:07 -0700
Re: scanf() James Kuyper <jameskuyper@verizon.net> - 2012-08-12 08:03 -0400
Re: scanf() Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-12 06:41 -0700
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-12 13:39 -0700
Re: scanf() Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-12 14:20 -0700
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-08-12 16:33 -0700
Re: scanf() "Heinrich Wolf" <invalid@invalid.invalid> - 2012-08-13 12:22 +0200
Re: scanf() Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-09-05 00:13 +0300
Re: scanf() Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 14:18 -0700
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-09-07 15:02 -0700
Re: scanf() Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 17:25 -0700
Re: scanf() Keith Thompson <kst-u@mib.org> - 2012-09-07 18:35 -0700
Re: scanf() Seungbeom Kim <musiphil@bawi.org> - 2012-08-12 21:05 -0700
Re: scanf() Robert Wessel <robertwessel2@yahoo.com> - 2012-08-11 17:37 -0500
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