Replace string key of PHP array

The most possible way you can get the numerical index represented by string is when you convert object with numeric property name to array.

More detailed this covered here

Works great for me

$ php -r '$foo = array("3" => 5); $foo["3"] = 6; print_r($foo);'
Array
(
    [3] => 6
)

The first is actually creating a numerically indexed array key, the second a string key. You can use type casting to force consistent behavior.

$test = array((string) '3' => 5);
$test[(string) '3'] = "New value";

Update, these behave identically for me on PHP Version 5.2.13:

$test = array('3' => 5);
echo '<pre>'.print_r($test,true).'</pre>';
$test['3'] = "New value";
echo '<pre>'.print_r($test,true).'</pre>';

$test = array((string) '3' => 5);
echo '<pre>'.print_r($test,true).'</pre>';
$test[(string) '3'] = "New value";
echo '<pre>'.print_r($test,true).'</pre>';