PHP生成固定字符串

I have a website that needs to generate a fixed prefixed strings and the order id as the invoice number.

The current code is $cnt = strlen($order->id);
$remain = 20-$cnt;
$data['invoiceNo'] = $this->generateRandomString($remain).$order->id;

How to i change it to have a prefix of JGJEPOSONLINECS + order id instead of random string + order id

Try with this code

$data['invoiceNo'] = 'JGJEPOSONLINECS'.$order->id ;