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Date: Sat, 15 Jan 2000 19:26:29 +0000
From: Ben Smithurst <ben@scientia.demon.co.uk>
To: Carlos Maracabay <caradusa@yahoo.com>
Cc: freebsd-questions@FreeBSD.ORG
Subject: Re: Language C on Freebsd Release 3.3 Question.
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Carlos Maracabay wrote:

> #include <stdio.h>
> #include <fcntl.h>
> #include <sys/types.h>
> #include <unistd.h>

fine, but I tend to put <sys/types.h> first, since other headers may depend
on it. It doesn't seem to matter here, though.

> main(int argc, char *argv[])

You should explicitly declare "main" as returning "int".

> if(argc != 2)
>   printf("Argument meesing\n");

You should probably exit() after printing that error message.

> if(f1 = open(argv[1], O_RDONLY,0) == -1)

Here's the real problem. You're assigning to "f1" the value of open(...)
== -1, which will be 1 if open fails, and 0 if it doesn't. this
will cause your code to try to read from standard input, or output,
respectively. You need parentheses around the "f1 = open(...)" part, as
you did in the n = read loop below.

If you compile with the -Wall flag to cc, you would have seen these
problems yourself. :-)

> printf("cp cant open \n");

again, you should exit, and it would be good practice to say which file
you can't open, and why (e,g, strerror(errno)).

> while((n = read(f1,buf,BUFSIZ)) > 0)
> if(write(1,buf,n) != n)               #I think here is
> my problem

no, that's fine.

-- 
Ben Smithurst            | PGP: 0x99392F7D
ben@scientia.demon.co.uk |   key available from keyservers and
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