Path: utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!wuarchive!udel!mmdf
From: AJB@dlvh.daresbury.ac.uk
Newsgroups: comp.os.minix
Subject: fopen() for update?
Message-ID: <34240@nigel.ee.udel.edu>
Date: 22 Oct 90 22:14:59 GMT
Sender: mmdf@ee.udel.edu
Lines: 27


I noticed in patching BISON for GNUC on the ST that the following code
segment doesn't work on either the ACK or GNUC (or PC?) compilers.

FILE *fp;
char line[10];

fp = fopen("anyfile","w+");
fprintf(fp,"Hello\nWorld\n");

rewind(fp);
fgets(line,10,fp);
printf("%s",line);

You definitely end up with a file containing the requisite text but the
rewind doesn't work (which is not surprising looking at fopen.c) hence
no 'Hello' is printed.
To get bison to work I had to fclose(fp) and fopen() with "r" in place of
the rewind().

BEWARE! the man pages I have says 'w+' is a valid option.

Alan Bleasby
SERC Daresbury Laboratory
Daresbury
Warrington UK
Email: AJB@UK.AC.DARESBURY.DLVH