Path: utzoo!attcan!uunet!husc6!purdue!haven!uvaarpa!mmdf
From: worley@compass.com (Dale Worley)
Newsgroups: comp.lang.perl
Subject: $! and string context
Message-ID: <1990Jul13.175014.1750@uvaarpa.Virginia.EDU>
Date: 13 Jul 90 17:50:14 GMT
Sender: mmdf@uvaarpa.Virginia.EDU (Uvaarpa Mail System)
Reply-To: worley@compass.com
Organization: The Internet
Lines: 24

People might be interested to note that the conditional expression in
an 'if' is a string context, which I didn't expect.  The
string/numeric context difference seems to usually be unimportant, but
$! is an exception:

	die "Can't do ..." if $!;

does not work, since if there is no error, $! in a string context will
give 'Error 0', which tests TRUE.  For another example, run the
program:

	$a = $! + 0;
	print "numeric is $a\n";
	print "string is $!\n";
	if ($!) {
		print "tests TRUE\n";
	} else {
		print "tests FALSE\n";
	}

Dale Worley		Compass, Inc.			worley@compass.com
--
Don't go around saying the world owes you a living. The world owes you
nothing. It was here first. -- Mark Twain