Question

How do I execute the transaction(123) function?

The response via API is: transaction(123)

I store this in the $response varible.

<?php

function transaction($orderid) {
  return  $orderid;
}

//api response
$response = "transaction(123)";

try {
  $orderid = call_user_func($response);
  echo  $orderid;
} catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
}

?>

Answer 1

According to the manual page call_user_func() should be called with two parameters in your use case.

$orderid = call_user_func('transaction', 123);

This means you must extract the function and parameter separately from your $response variable:

preg_match('/([\w\_\d]+)\(([\w\W]*)\)/', $response, $matches);

Would result in the $matches array containing the function name at index 1 and the parameter at index 2.

So you would then do:

$orderid = call_user_func($matches[1], $matches[2]);

Obviously you need to be very careful with the values if they are coming from an untrusted source.