add item to end of (multidimensional) array

Hi, How can i add new items to an array without using an index. Normally (single dimension) you can do: Arr[]="xxxxx" and this item is added to the array, but what if i have subitems like: Arr[]['name']="arnold"; Arr[]['address']="street". This last example doesnt work and i think there will be an easy solution but who can tell me this? Arnold