PHP get previous array element knowing current array key

Question

I have an array with specific keys:

array(
    420 => array(...), 
    430 => array(...), 
    555 => array(...)
)

In my applicati

Answer 1

I solved this issue in this way:

function getPrevKey($key, $hash = array())
{
    $keys = array_keys($hash);
    $found_index = array_search($key, $keys);
    if ($found_index === false || $found_index === 0)
        return false;
    return $keys[$found_index-1];
}

@return previous key or false if no previous key is available

Example:

$myhash = array(
    'foo' => 'foovalue',
    'goo' => 'goovalue',
    'moo' => 'moovalue',
    'zoo' => 'zoovalue'
);

echo "TEST: ". getPrevKey('zoo', $myhash); // prints moo