$re = '/(X|Y|Z|A3=|B3=|C3=)(\-?\d+(?:\.\d+)?)/';
$str = 'X2 G1 X-387.7 A3=-1.0 B3=0.0 C3=0.0 F=R3
Y1.824 Z264.663 A3=-1.0 C3=0.0 YY123.4 3X213.3';
preg_match_all($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