in fact, your code shouldn't be some thing like
    my $pattern = qr{ab[crdnfqm]def};
        if $string =~ m{ ($pattern) };
                 ....
which doesn't find all strings with the pattern.

That is perhaps because the regex  m{ ($pattern) } (which lacks the  /x regex modifier) requires a space before and after  $pattern in order to match.

I don't understand trailing xms at the end of pattern.

These are regex modifiers. The  /x modifier makes the regex compiler ignore whitepace (for improved readability). The  /m and  /s modifiers control the behavior of, respectively, the  ^ $ (string end) and  . (dot) metacharacter operators. I have adopted the best practice recommended by TheDamian of always (well, almost always) including these modifiers in every  qr// m// s/// regex I write. The reason for this is to improve regex readability (/x) and to make explicit the behavior of the  ^ $ . operators (/ms).

Please see perlre, perlrequick, and perlretut.

In reply to Re^5: search of a string in another string with 1 wildcard by AnomalousMonk
in thread search of a string in another string with 1 wildcard by carolw

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