Re: Testing <> for undefined

Here's something that I use in most of my scripts:

Assuming the scriptname is called file_parse.pl, and you're trying to pass it single file only:

if ($#ARGV != 0) {
   print "Usage: file_parse.pl [filename] \n";
   exit(1);
}
[download]

Trek

Comment on Re: Testing <> for undefined Download Code

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•Re^2: Testing <> for undefined by merlyn (Sage) on Jul 07, 2004 at 16:52 UTC
This code scares me. If you want to see if there is one argument, use `@ARGV` in a scalar context, comparing it to one. I could easily imagine people reading this code and not remembering that `$#ARGV` is one less than the number of arguments, and being very confused. My rule is, use `@ARGV` when you want to talk about the number of elements, and reserve `$#ARGV` for getting the ending index for ranges. -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply]
Re^3: Testing <> for undefined by TrekNoid (Pilgrim) on Jul 07, 2004 at 17:21 UTC
My rule is, use @ARGV when you want to talk about the number of elements, and reserve $#ARGV for getting the ending index for ranges. Thanks, merlyn... It's one of those things I learned to do one way when I was first learning Perl, and have never gone back and revisted it... There's just so few things I can help people with in Perl, that I get excited when I see one I can answer :) Guess I'm destined to remain an acolyte for the foreseeable future :) I'll make a note for future development Trek	[reply]


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