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Postings from March 2022
demerphq <demerphq@gmail.com> [2022-03-12 14:23:12 +0800]:
> On Sat, 12 Mar 2022, 05:19 William Lindley, <wlindley@wlindley.com> wrote:
>
> > In all this discussion, what happens when reading a file
>
>
> Any data that was read from a file would be a string unless you did
> something to tell perl otherwise.
>
> containing the
> > line:
> >
> > 01730
> >
> > which is the postal code for my hometown. This "looks like" a number
>
>
> I don't believe it does actually. The leading 0 means that
> looks_like_number() should reject it.
>
Could you expand a bit on what you meant above by "should reject"?
I didn't understand if you meant it in the sense of "should be rejected
by looks_like_number() as implemented in the upcoming Perl release", or
if you meant more generally that rejection "should be the current _and_
future behavior".
I'm asking because my experience with looks_like_number() has been (for
many years, up to and including 5.34) based on the attached script and
set of test case strings, several of which have leading zeros. TTBOMR,
the leading-zeros cases in the first group have always been classified
as "a number" by Scalar::Util::looks_like_number().
I added a few more cases just now for a little better test coverage,
and all seem to still accord with my historical (and present) expectations
as a Certified Perl Moron. Am I making some mistake in the way that the
test script makes its determination?
Are any of these test cases expected to change in the upcoming release?
Thanks,
Glenn
========================== TEST SCRIPT ===================================
#!/usr/bin/perl
use 5.034;
use warnings;
use strict;
use Scalar::Util qw / looks_like_number /;
my $lln;
while (<STDIN>)
{
chomp;
if (/^#/) { print "$_\n"; next; }
if (/^$/) { print "\n"; next; }
$lln = looks_like_number($_) ? " looks like" : " doesn't look like";
$lln .= " a number";
printf("%25s %-30s\n", "'${_}'", $lln);
}
=============================================================================
======================== TEST CASES =====================================
#
# Morons expect "looks_like_number()" to succeed:
#
123
+123
-123
123.4
123.4E5
123.4E05
123.4E+5
123.4E+05
123.4E+000000005
123.4E-000000005
123.4e-000000005
0000123.4E-000000005
123E+456789
0123
+0123
-0123
0123.4
0123.4E5
0123.4E05
0123.4E+5
0123.4E+05
0123.4E+000000005
0123.4E-000000005
0123.4e-000000005
0000123.4E-000000005
0123E+456789
0
+0
-0
Inf
Infinity
+Inf
-Inf
inf
InFiniTy
-InFiniTy
#
# Morons expect "looks_like_number()" to fail:
#
123.4E-+000000005
123.4E+-000000005
123.4g-000000005
123E+4.5
0123.4E+-000000005
0123.4E-+000000005
0123.4g-000000005
0123E+4.5
0x123
0x0123
A Number
=============================================================================
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