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Re: regex negative numbers

by bjelli (Pilgrim)
on Aug 28, 2002 at 08:13 UTC ( #193385=note: print w/replies, xml ) Need Help??


in reply to regex negative numbers

To summarize: the problem is in the pattern, (or in the fact that you didn't check if the pattern mached at all).

I've changed three things about the pattern:

  1. ? instead of {0,1}
  2. ^ just once
  3. \d+ instead of \d*
  4. discarded the /m at the end
while (<DATA>) { chomp; print "Test case '$_'\n"; if ( m!^(-?\d+)\s+(-?\d+)! ) { print "$_, " for ($1 .. $2); } else { print "doesn't match"; } print "\n\n"; } __DATA__ 1 6 -4 6 -4 -1 6 1 6 -4 -1 -4

making the program count *backwards* is left as an exercise to the reader.

--
Brigitte    'I never met a chocolate I didnt like'    Jellinek
http://www.horus.com/~bjelli/         http://perlwelt.horus.at

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[Eily]: you could tie a variable into not having the same value each time, if you like to make people who try to debug your code facepalm
[Corion]: perl -wle 'package o; use overload q("") => sub {warn "str"; ""}, bool => sub{warn "bool"; 1}; package main; my $o={}; bless $o => o; print "Yay" if ($o && !length($o))'
[Corion]: But people writing such code should document the objects they construct and why it makes sense for an object to be invisible as string while being true in a boolean context
[hippo]: That's equal parts clever and horrendous.
[Eily]: the overload version wouldn't return true with "$x" && !length $x though, I guess
[hippo]: The more I look at this code, the more $x is a plain old scalar and the more this condition will never be true. I'm calling it a bug at this point.
[hippo]: Thanks for your input which has soothed my sanity (a little)
[Corion]: Eily: Sure - if you force both things into stringy things, then you break that magic. But that would also mean that you changed the expression, as now $x = 0.00 will be true instead of false as it were before
[Corion]: Ah no, at least in my feeble experiments that doesn't change the meaning
[Corion]: We sell sanity in small packages ;)

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