php - Regular Expression for Screen Solution -

i have following string

540x360 [par 1:1 dar 3:2]  

the result want

540x360 

how can , please suggest in future able solve these kind of problem self.

if want use regular expression can use:

$string = "540x360 [par 1:1 dar 3:2]"; $matches = array(); preg_match('/^(\d+x\d+)/i', $string, &$matches); echo $matches[0];