Odd closing brace issue

broomnew has asked for the wisdom of the Perl Monks concerning the following question:

I'm not silly enough to think I've found a bug, I must be doing something I simply don't understand.

Using perl 5.8.4.

I typod and missing the closing curly brace in a numeric range in a regular expression. It did not error out, only missed the matches I expected in my test.

Would this be considered correct behaviour?

Sample code:

#!/usr/bin/perl -w

use strict;

while (<DATA>){
    chomp;
    #
    # Incorrect REGEXP - missing closing curly   !
    #                                            V
    if (/(&[A-Z0-9\.]+:LU)((\d{1,2};\d{1,2})|(\d{1,2)|LD|LC)?/){
        my $lookup = $1;
        my $type = $2;
        $type ||= '';
        print "1. Lookup: [$lookup]:[$type]:[$_]\n";
    }
    #
    # Correct REGEXP - notmissing closing curly  !
    #                                            V
    if (/(&[A-Z0-9\.]+:LU)((\d{1,2};\d{1,2})|(\d{1,2})|LD|LC)?/){
        my $lookup = $1;
        my $type = $2;
        $type ||= '';
        print "2. Lookup: [$lookup]:[$type]:[$_]\n";
    }
}

__DATA__
&&STOP                                                                
&&JUMP(&VAR2:LU,NE,SPACES)026
&&JUMP(&VAR2:LU2,NE,SPACES)026
&&JUMP(&VAR2:LU23,NE,SPACES)026
&&JUMP(&VAR2:LU23;24,NE,SPACES)026
&&JUMP(&VAR2:LULD;24,NE,SPACES)026        
&&JUMP(&VAR2:LULC;24,NE,SPACES)026
&&JUMP027
[download]

Comment on Odd closing brace issue Download Code

Replies are listed 'Best First'.
Re: Odd closing brace issue by derby (Abbot) on Apr 08, 2005 at 18:31 UTC
Not really. From the perlre: The following standard quantifiers are recognized: * Match 0 or more times + Match 1 or more times ? Match 1 or 0 times {n} Match exactly n times {n,} Match at least n times {n,m} Match at least n but not more than m times (If a curly bracket occurs in any other context, it is treated as a regular character. In particular, the lower bound is not optional.) So in the Incorrect regex is valid - match any digit followed by, literally, {1,2 (&&JUMP4{1,2SCOOBY would match). -derby	[reply]
Re: Odd closing brace issue by tlm (Prior) on Apr 08, 2005 at 18:33 UTC
Add this line to your data, and you'll see what's happening: `&&JUMP(&VAR2:LU2{1,2foobarbaz` [download] the lowliest monk	[reply] [d/l]