The documentation for array_walk() states that the function being called will be passed two parameters; specifically it states, "func will be passed array value as the first parameter and array key as the second parameter."  array_walk() is passing the first parameter but is failing to pass the second one which is the key.

The example code supplied at http://www.php.net/manual/function.array-walk.php3 gives the following errors:

Warning: Missing argument 2 in call to test_print() in /usr/local/apache/htdocs/test.php on line 8
. lemon

Warning: Missing argument 2 in call to test_print() in /usr/local/apache/htdocs/test.php on line 8
. orange

Warning: Missing argument 2 in call to test_print() in /usr/local/apache/htdocs/test.php on line 8
. banana

Warning: Missing argument 2 in call to test_print() in /usr/local/apache/htdocs/test.php on line 8
. apple

for the following code from the array_walk() documentation page:

<?php
$fruits = array("d"=>"lemon","a"=>"orange","b"=>"banana","c"=>"apple");

function test_alter( &$item1, $key, $prefix ) {
   $item1 = "$prefix: $item1";
}

function test_print( $item2, $key ) {
   echo "$key. $item2<br>\n";
}

array_walk( $fruits, 'test_print' );
// array_walk( $fruits, 'test_alter', 'fruit' );
// array_walk( $fruits, 'test_print' );
?>

This seems to be a bug as the documentation states that the value and key are passed to the function specified in array_walk().  However, only the value is being passed while the key is omitted.