use Test::More;

my @match_wanted = qw( abc bca cab cba bac acb );
my @match_unwanted = qw( aab abbc acc );
sub match {
    my $s = shift;
    return ( ($s =~ /(?:[abc].*){3}/) && ! ($s =~ /([abc]).*\1/) );
}

plan 'tests' => ( scalar @match_wanted + scalar @match_unwanted );

ok( match( $_ ), "matches '$_'" )          for @match_wanted;
ok( ! match( $_ ), "does not match '$_'" ) for @match_unwanted;

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In reply to Re: REgular expression to check the string that allows "a","b" and "c" to occur only once in any order. by kyle
in thread REgular expression to check the string that allows "a","b" and "c" to occur only once in any order. by isha

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