$re = '/array<struct<(.*?)>>/';
$str = 'pchase_history:array<struct<pchase_channel:string,trans_dt:string,sku_id:string,sold_qty:bigint>>,first_pchase_dt:string,last_pchase_dt:string,trans_cnt:bigint,last_pchase_sku_cnt:bigint,no_of_pchase_days:bigint,lst_pchase_channel:array<struct<pchase_channel:string>>';
preg_match_all($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