nl2br converts true to int and false to empty string

Question

I am using PHP Version 5.6.25. The following code is all that's needed to replicate the issue.

$data['foo'] = true;
$data['bar'] = false;
var_dump($data);
$data['foo'] = nl2br($data['foo']);
$data['bar'] = nl2br($data['bar']);
array_walk_recursive($data, "filter");
var_dump($data);

This gives the following result.

array (size=2)
  'foo' => boolean true
  'bar' => boolean false
array (size=2)
  'foo' => string '1' (length=1)
  'bar' => string '' (length=0)

Is this a PHP bug? Is there a workaround?

Answer 1

from the manual nl2br

string nl2br ( string $string [, bool $is_xhtml = true ] )

nl2br expects a string as an input, casting a boolean to a string returns 1 for true and "" for false; so no surprises that's what you get in this case.

In your filter function you can check the variable type before deciding how to filter it.