Changing order of just one array item?

I need to change where one item is ordered in an array. I know how to sory an array, but I need to move one item up/down in the array. Example: $array is: 0 => "element one" 1 => "element two" 2 => "element three" 3 => "element four" I call array_order_up($array[1]) and $array is now: 0 => "element one" 2 => "element three" 1 => "element two" 3 => "element four" If there aren't any native functions to do this, can anyone think of a way to make my own function to do this? -- The above message is encrypted with double rot13 encoding. Any unauthorized attempt to decrypt it will be prosecuted to the full extent of the law.