programming-for-dummies

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Data Structures
The array name can be any descriptive name. The array size defines how
many items the array can hold. Because the array is zero-based, an array
defined as a size 10 can actually hold 11 items. The data type defines the
type of data the array can hold, such as all strings or all integers. To create
an array that can hold 11 strings, you could define an array like this:
DIM PetNames (10) AS String
If you want an array to grow or shrink while your program runs, you can
define a dynamic array. To define a dynamic array, omit the array size and
then define the array size right before you start storing items into that array,
such as
DIM ArrayName () AS DataType
REDIM ArrayName (ArraySize)
The REDIM keyword tells the program to resize the array.
Creating a collection and a dictionary
Arrays can be too restrictive because they can only hold one data type. For a
more flexible alternative, use a collection instead. Two big advantages of a
collection over an array are that a collection can hold different data types
and can grow and shrink without having to define its size. To define a collection,
define a collection name as follows:
DIM Name AS NEW COLLECTION
Unlike arrays where the first item is assigned an index number of 0, a collection
assigns the first item an index number of 1.
A variation of a collection is a dictionary (available only in REALbasic). The
two main advantages of a dictionary are that you can assign descriptive
values, or keys, to each item stored in a dictionary. This makes it easier and
faster to retrieve data.
To retrieve an item from a dictionary, specify the key. To retrieve an item
from an array or a collection, you must either know the exact position of the
item you want or you must search the entire array or collection to find the
data you want. As a result, searching for items in a dictionary is much faster
and easier than searching for items in arrays or collections.