[TriLUG] perl: how to initialise a variable that I want to be NULL
Joseph Mack NA3T
jmack at wm7d.net
Mon Aug 17 21:26:05 EDT 2009
Hi Michael, Shawn
> Something else is wrong with your code, that should work.
> Are you sure single quotes didn't work?
It didn't yesterday, but today it works fine. (Presumably I
could go back to yesterday afternoon's code to find out why,
but for the moment, I'll just take working code). This code
does all the expected things
#! /usr/bin/perl
use strict;
use warnings;
my $query_string = "";
$query_string = "foo " . $query_string; # string is already initialised
$query_string = '';
$query_string = "foo " . $query_string; # string is already initialised
undef($query_string);
$query_string = "foo " . $query_string; # string not initialised
$query_string = undef;
$query_string = "foo " . $query_string; # string not initialised
> ... that's not kludgy. It's just the way things are. It
> wouldn't matter what programming language you are using.
Yes, I realised this as soon as I saw the problem. I had
expected that '' would do as an initialised value (which
should have worked, but there must have been something wrong
with my code yesterday). I could also see the logic in ''
being undef, but if that was the case, then what did I use
to initialise a string. It turns out that both '' and ""
work.
Thanks Joe
--
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!
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