$re = '/^([^-]*?)\s*-\s*/m';
$str = '123 - foo - asdf
234 - bar - abcdefg
345 - foobar and hello world';
$subst = "$1, '";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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