Xref: utzoo comp.sys.ibm.pc:28245 comp.binaries.ibm.pc.d:2873
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!novavax!infocenter!mhoffman
From: mhoffman@infocenter.UUCP (Mike Hoffman)
Newsgroups: comp.sys.ibm.pc,comp.binaries.ibm.pc.d
Subject: Re: HELP need in C (turbo c, fopen problem)
Message-ID: <2172@infocenter.UUCP>
Date: 2 May 89 13:11:57 GMT
References: <1372@naucse.UUCP>
Organization: Gould CSD, Fort Lauderdale, FL
Lines: 40

in article <1372@naucse.UUCP>, wew@naucse.UUCP (Bill Wilson) says:
> 
> From article <353@h.cs.wvu.wvnet.edu>, by packer@a.cs.wvu.wvnet.edu (Michael A Packer):
>> 
>> i am trying to open a file.  When i open the file my filepointer is 
>> being returned (not null).  When i look at what fp is pointing to
>> there is garbage in the "buffer" and "curp" as declared by FILE.
>> 
>> if ((fp=fopen("junk.dat","w"))==NULL)
>>  {
>>   printf ("Can't open file\n");
>>   return;
>>  }
>>
> For example to read from the stream, you could use the following:
> 
> while (!feof(in))
>       putc(fgetc(fp));
>       

Maybe I missed something in the translation, but when you fopen() a 
file with a type argument of "w", the file is either created (if it 
didn't already exist), or truncated to a length of zero (if it did
exist). Therefore, no reads could be done. 

To open a file for read, use "r"; for reading and writing "r+"
To open for append at the end of the file (or create if it
doesn't exist) use "a".
To truncate or create but allow reads, use "w+".

The difference between "r+" and "a" is the position of the stream
pointer into the file.

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Michael J. Hoffman                                    Voice: (407)255-8116
Manufacturing Engineering                               FAX: (407)255-8186
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