Paul Lalli wrote:
On Aug 9, 10:07 am, [EMAIL PROTECTED] (Oryann9) wrote:
Paul, what college?
Rensselaer Polytechnic Institute, Troy, NY
http://www.cs.rpi.edu/~lallip/perl/spring07
On that page at the Sunday, March 25, 2007 entry:
if (! $value) { ... } # $value is either 0, '', '0', or undef
if ($value == 0) { ... } # $value is either 0, '', '0', or undef - but will
issue a warning for '', '0', or undef
if (!defined($value)) { ... } # $value is undef
0 and '0' are numerically equivalent so only '' and undef would issue a warning.
$ perl -le'
use warnings;
use strict;
my $c = 1;
for my $x ( 0, q[], q[0], undef ) {
print $c++, ": $x" if $x == 0;
}
'
1: 0
Argument "" isn't numeric in numeric eq (==) at -e line 6.
2:
3: 0
Use of uninitialized value in numeric eq (==) at -e line 6.
Use of uninitialized value in concatenation (.) or string at -e line 6.
4:
John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall
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