I think there is a bug in an example on the in_array()'s manual page.
Example 3:
<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');

if (in_array(array ('p', 'h'), $a))
    echo "'ph' is found\n";
if (in_array(array ('f', 'i'), $a))
    echo "'fi' is not found\n";
if (in_array('o', $a))
    echo "'o' is found\n";
?>

// This will output:

'ph' is found
'o' is found

-=-=-=-=-=-
Either the message for the second "if" must be :
"'fi' is found\n"
or
the condition must be changed as well as the output
if (!in_array(array ('f', 'i'), $a))

Output:
'ph' is found
'fi' is not found
'o' is found

Regards,
Andrey