in_array() and multidimensional array

If you know which column to search against, you can use array_search() and array_column():

$userdb = Array
(
    (0) => Array
        (
            ('uid') => '100',
            ('name') => 'Sandra Shush',
            ('url') => 'urlof100'
        ),

    (1) => Array
        (
            ('uid') => '5465',
            ('name') => 'Stefanie Mcmohn',
            ('url') => 'urlof5465'
        ),

    (2) => Array
        (
            ('uid') => '40489',
            ('name') => 'Michael',
            ('url') => 'urlof40489'
        )
);

if(array_search('urlof5465', array_column($userdb, 'url')) !== false) {
    echo 'value is in multidim array';
}
else {
    echo 'value is not in multidim array';
}

This idea is in the comments section for array_search() on the PHP manual;

This will work too.

function in_array_r($item , $array){
    return preg_match('/"'.preg_quote($item, '/').'"/i' , json_encode($array));
}

Usage:

if(in_array_r($item , $array)){
    // found!
}

in_array() does not work on multidimensional arrays. You could write a recursive function to do that for you:

function in_array_r($needle, $haystack, $strict = false) {
    foreach ($haystack as $item) {
        if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
            return true;
        }
    }

    return false;
}

Usage:

$b = array(array("Mac", "NT"), array("Irix", "Linux"));
echo in_array_r("Irix", $b) ? 'found' : 'not found';