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From: oae@intrin.UUCP
Newsgroups: comp.lang.c
Subject: A question about stdin, stdout and stderr
Message-ID: <487@intrin.UUCP>
Date: Fri, 20-Feb-87 08:29:03 EST
Article-I.D.: intrin.487
Posted: Fri Feb 20 08:29:03 1987
Date-Received: Thu, 26-Feb-87 22:23:47 EST
Reply-To: oae@intrin.UUCP (Olavi Eerola)
Organization: Intrinsic Oy, Tampere, FINLAND
Lines: 39
Keywords: standard-io lex vms vax c


I have a problem. I generated a program with lex on ULTRIX and moved
that program to VMS. On VMS I got an error message from the next line:

FILE *yyin = {stdin}, *yyout = {stdout};
	
The VMS's C compiler didn't translate these initializations, because
stdin and stdout are variables on VMS. On ULTRIX they are constants.
Then I examined The Father, The Son and The Holy Ghost and found
the following:

1. The K&R, p 153, says:

	"The file pointers stdin and stdout are pre-defined in the I/O
	 library as the standard input and standard output; they may be
	 used anywhere an object of type FILE * can be. The are constants,
	 however, not variables, so don't try to assign to them."
	 
	 
2. Harbison, Steele: A C Reference Manual, p 316, says:

	"11.5.32 stdin
	 ..., the external variable stdin will contain a stream that..."

	"11.5.33 stdout
	 ..., the external variable stdout will contain a stream that..."

3. As for I know the draft ANSI C standard says that stdin, stdout and
   stderr are expressions.

So, are they constants, variables or expression? I think that The K&R
has the only right definition for stdin, stdout and stderr, the others
are wrong.


Olavi Eerola			oae@intrin.uucp
Intrinsic Oy
Aleksis Kiven katu 11 C
SF-33100 Tampere, Finland	+358-31-132800