Re: [MacPerl] <> warning

[Adrian Howard <adrianh@victoriareal.co.uk>]

Not really a MacPerl question... but since I have something better to do :-)

At 3:07 pm +0100 28/7/98, William B. Birkett wrote:
>When I run a program containing the following lines,
>
>    while ($line = <IN_FILE>) {
>        print $line;
>    }
>
>I get the following warning,
>
># Value of <HANDLE> construct can be "0"; test with defined().
>File 'Untitled'; Line 10
>
>The reason I am using $line is that I have another file opened and don't
>want to alter the $_ variable. This construct is in the MacPerl P&E book,
>so I assume it is commonly used.
>
>The program executes properly, but I am bothered by the warning. What does
>the warning mean? Is there a better way to write this code?
>
>
>William B. Birkett

Imagine IN_FILE consists of the following

	5\r
	4\r
	3\r
	2\r
	1\r
	0

Now, since the last line doesn't have an end-of-line character $line will
equal "0" which equates to false, so it doesn't get printed. Probably not
what you wanted to happen.

Just do something like

	while (defined($line = <IN_FILE>)) {
		print $line;
	}

to get the "correct" behaviour.

Hopefully this makes sense :-)

Cheers,

Adrian

>Precision Color, Inc.
>9200 General Drive
>Plymouth, MI 48170 (USA)
>
>Phone: (734) 459-5640
>FAX:   (734) 459-4210
>
>
>
>
>***** Want to unsubscribe from this list?
>***** Send mail with body "unsubscribe" to mac-perl-request@iis.ee.ethz.ch


----
Adrian Howard. adrianh@victoriareal.co.uk. Head Techie. Victoria Real Ltd
URL: http://www.victoriareal.co.uk/ v. +44 1273 774469 f. +44 1273 779960



***** Want to unsubscribe from this list?
***** Send mail with body "unsubscribe" to mac-perl-request@iis.ee.ethz.ch