Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!TAURUS.BITNET!asaph
From: asaph@TAURUS.BITNET
Newsgroups: comp.sys.amiga
Subject: Re: C scanf question
Message-ID: <1059@taurus.BITNET>
Date: 25 Jul 89 21:41:39 GMT
References: <20201@louie.udel.EDU> <455@tardis.Tymnet.COM>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: asaph%math.tau.ac.il@CUNYVM.CUNY.EDU (Zemach Asaph)
Organization: Tel-Aviv Univesity Math and CS school, Israel
Lines: 34

In article <455@tardis.Tymnet.COM> jms@tardis.Tymnet.COM (Joe Smith) writes:
>If you have "char line[80]" and use fscanf(f,"%s",line), what happens if
>the input has more than 80 consecutive characters without a tab, blank
>or newline?
>The only safe way to use the scanf family on untrustworthy data is to
>use sscanf on a string read by fgets or equivalent.
>
>Joe Smith (408)922-6220 | SMTP: JMS@F74.TYMNET.COM or jms@tymix.tymnet.com

   according to the manx 3.2 book you can limit the amount of chars read from
a file via scanf by using a line like this

char buffer[50]

:
:
fscanf (file,"%50s",buffer)
this should read no more then 50 chars including the null terminator.
for a more general read you could do

char buffer[BUFFSIZE]
fscanf (file,"%*s",BUFFSIZE,buffer) <-- I'm not sure about this one though!
If it doesn't work you might have to create the string "%" + num + "s", using
something like sprintf, for instance. (Talk about overkill !).
BTW, the the %+num+char is good for all types %2d will read a decimal number
of no more then 2 chars.
  As for the parsing usefullness of scanf I have this to contribute:
We where just recently given a project to do here at TAU, a sort of assembler
program, needles to say some line parsing is nessaccery there, I know that
some of my friend used sscanf extensively for this. after all the ability
to say %[ ~abcd] is pretty nice. I actualy wrote a small pattern matcher
but thats another story altogether.
                                        asaph
asaph@taurus.bitnet     - or -          asaph@math.tau.ac.il