$re = '/^([^-]+ - ){2}[^- ]+$/m';
$str = 'abc - xyz - 123
abc - xyz - 123 - a
- - - - -
_ - ____ - _
÷÷ - ÷ - ÷÷÷
- - x
-- [^-] pega quebras de linha
abc - fad
fdas - fda';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php