call_user_func_array() passes array as string bug?

Question

I'm using PHP 5.4.25. Take the following code:

<?php

function works($params=[])
{
    var_dump(is_array($params));
    var_dump($params);

    $params = (array) $params;

    var_dump(is_array($params));
    var_dump($params);

    $params['first_name'] = "Bob";
}

function fails($params=[])
{
    var_dump(is_array($params));
    var_dump($params);

    $params['first_name'] = "Bob";
}

call_user_func_array('works', ['first_name'=>'John', 'last_name'=>'Doe']);
call_user_func_array('fails', ['first_name'=>'John', 'last_name'=>'Doe']);

Results:

bool(false)

string(4) "John"

bool(true)

array(1) {
  [0] =>
  string(4) "John"
}

bool(false)

string(4) "John"

PHP Warning:  Illegal string offset 'name' in /vhosts/site/test.php on line 14
PHP Stack trace:
PHP   1. {main}() /vhosts/site/test.php:0
PHP   2. call_user_func_array() /vhosts/site/test.php:17
PHP   3. fails() /vhosts/site/test.php:17

It appears that the array passed is not a valid array... It shows only the first value of the array and as a string instead of an array... But you can then cast the string as an array and then it works fine.....

The solution is obviously to just cast it as an array at the beginning of the function, but it seems like you shouldn't have to do this. Is this a PHP bug? I can't seem to find any other reports of this.

To pass an actual array argument into fails: call_user_func_array('fails', [['first_name'=>'John', 'last_name'=>'Doe']]); — Mark Baker
– Mark Baker, Commented Aug 8, 2014 at 17:24

dave · Accepted Answer · 2014-08-08 17:28:07Z

6

This is not a bug, call_user_func_array() takes an array, and passes it into a function as individual arguments.

If you have a function do_something($a, $b, $c) you can do call_user_func_array("do_something", array(1, 2, 3)) and it will call do_something(1, 2, 3). If you just need to call the function and pass the array as an argument, you can use call_user_func.

It sounds like you want to do:

call_user_func('works', ['first_name'=>'John', 'last_name'=>'Doe']);

If you insist on using call_user_func_array, I suppose you could do:

call_user_func_array('works', [['first_name'=>'John', 'last_name'=>'Doe']]);

Which is passing an array of arrays, so it will take the single element in the array and pass it as the argument to the function.

Another options, if the method is dynamic, is to simply do something like this:

$method = "works";
$method(['first_name'=>'John', 'last_name'=>'Doe']);

edited Aug 8, 2014 at 17:28

answered Aug 8, 2014 at 17:16

dave

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2 Comments

Jake Wilson Over a year ago

Interesting. How come I can cast the first argument as an array and get the whole passed array then?

kjdion84 Over a year ago

You could json encode or serialize the array and pass it as that, then in your function json decode/unserialze it.

Michael Arrison · Accepted Answer · 2018-11-07 21:41:08Z

1

Although the original question asked about PHP 5.4.25, in versions since PHP 5.6, the answer can be simplified with the triple dot variable-length argument lists feature.

call_user_func_array('foo', ['a', 'b', 'c']);

function foo(...$params) {
  // $params = ['a', 'b', 'c']
}

http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list

answered Nov 7, 2018 at 21:41

Michael Arrison

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