Online PHP editor | output for 6mMbN

<?php $currencies = [ 'USD', 'BTC', 'DASH', 'LTC', 'SC', 'STEEM', 'WAVES', 'SNGLS', '1ST', 'BQX', 'ETH', 'PTOY', 'XAUR', ]; $input = [ "BTCUSD", "DASHBTC", "DOGEUSD", "LTCBTC", "LTCUSD", "SCBTC", "STEEMBTC", "WAVESBTC", "SNGLSBTC", "1STBTC", "DASHUSD", "BQXETH", "PTOYETH", "XAURETH", "BTCUSDT", ]; $output=[]; foreach($input as $doubleCurrency){ foreach($currencies as $currency){ $pattern = '/^'.$currency. '/'; preg_match($pattern, $doubleCurrency, $matches); if(array_key_exists(0, $matches)){ $output[]=$matches[0]; } } } var_dump($output);