Hi Monks

I am looking for a RegEx which search for 'ax', not followed by 'ba' and preplaces this string.

I have two not fully working solutions:

1) One with look ahead => Problem: The chars in the look ahead are not replaced => first term in @reg

2) With two not char sets => Problem: The two charsets are looked speratly, not in combination => second term in @reg.

Many thanks for any help !!

Please find here my testbench: 

use strict;
use warnings;

use Test::More;
$\="\n";

#  search for 'ax', not followed by 'ba'
my @teststr = ('0axba',      # simple not ok
               '1axbb',      # one char ok, one not 
               '2axccaxdd',  # simple 2 times
               '1axbaxcc',   # one time (sequence combined)
               '1axcaxcc'    # one time (sequence combined)
              );

my @reg = ( qr/ax(?!ba)/,     # look ahead
            qr/ax[^b][^a]/,   # 2 not char sets
         );

plan tests => @teststr*@reg;

for my $re (@reg) 
{ print "---------------\n$re\n---------------";
  for my $str (@teststr) 
  { my $str1=$str; my $str2=$str; # get teststring
    $str1=~s/^\d//;               # remove result
    my $got = $str1=~s/$re/-/g;   # replace (do test)
    $str2=~s/^(\d)//;             # remove result and remember
    cmp_ok($got, '==', $1, "($1) $str2 => $str1  ");  #check
} }

[download]
Program output => 
1..10
---------------
(?^:ax(?!ba))
---------------
ok 1 - (0) axba => axba
ok 2 - (1) axbb => -bb
ok 3 - (2) axccaxdd => -cc-dd
ok 4 - (1) axbaxcc => axb-cc
not ok 5 - (1) axcaxcc => -c-cc
#   Failed test '(1) axcaxcc => -c-cc  '
#   at Y:\atp01082\data\data\Perl\test\regex_not.pl line 30.
#          got: 2
#     expected: 1
---------------
(?^:ax[^b][^a])
---------------
ok 6 - (0) axba => axba
not ok 7 - (1) axbb => axbb
#   Failed test '(1) axbb => axbb  '
#   at Y:\atp01082\data\data\Perl\test\regex_not.pl line 30.
#          got:
#     expected: 1
ok 8 - (2) axccaxdd => --
ok 9 - (1) axbaxcc => axb-
ok 10 - (1) axcaxcc => axc-
# Looks like you failed 2 tests of 10.

[download]

In reply to RegEx : search for 'ax', not followed by 'ba' by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.