Hi,

Disclaimer: I am not a regex wizzard, so I'm not sure if the following has any pitfalls, but it does appear to be possible with a single regex:

print $_, /(x(.*)x(??{ '.{'.length($2).'}' })x)/
    ? " matches, \$1 = $1\n" : " doesn't match\n"
        for qw/ xxx x.x.x x12x..x x123x...x x1x2x...x
            x123x.x.x x12x1x ax1x2xbx34x56xc /;

__END__

xxx matches, $1 = xxx
x.x.x matches, $1 = x.x.x
x12x..x matches, $1 = x12x..x
x123x...x matches, $1 = x123x...x
x1x2x...x matches, $1 = x1x2x...x
x123x.x.x matches, $1 = x123x.x.x
x12x1x doesn't match
ax1x2xbx34x56xc matches, $1 = x1x2xbx34x56x

[download]

Update: Changing the first part of the regex to x(.*?)x (non-greedy) will allow you to match all the substrings in that last example above (and the rest of the examples above will continue to work the same):

my $re = qr/(x(.*?)x(??{ '.{'.length($2).'}' })x)/;
my $str = "ax1x2xbx34x56xc";
while ($str=~/$re/g) {
    print "found \"$1\"\n";
}

__END__

found "x1x2x"
found "x34x56x"

[download]

Hope this helps,
-- Hauke D

In reply to Re: Regular Expression: search two times for the same number of any signs (updated) by haukex
in thread Regular Expression: search two times for the same number of any signs by Anonymous Monk

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