Arrays in Visual Basic are handled differently then their counter parts in Java, PHP, and Ruby. The first difference is that you specify array index by use of parenthesis not square brackets.
Java Array Initialization
String myArray = new String;
Visual Basic Array Initialization
Dim myArray(19) As String
Looking over the two arrays you may think that the Array in VB only can hold 19 elements this is incorrect. Visual Basic uses a 0 based index meaning that in actuality it holds elements at indexes 0 through 19 or 20 total items.
Fixed Length Array
When you specify the array’s dimension when declaring the array you have created it as a Fixed length Array this means that you can not change its size and decide you want to add a 21st item to an array of 20 items. To access or set an item in an array you simply need to call the variable with it’s index wrapped in parenthesis.
Dim myArray(2) As String myArray(0) = "Matthew" myArray(1) = "Apollo" myArray(2) = "Joseph" Dim aName As String aName = myArray(1)
Dynamic Length Array
Sometimes you will not know the full size of the array you will need to create. In these cases you can create a Dynamic Length Array, these arrays allow you to change their size by re defining their length while preserving their contents. To define your Dynamic Array you simply don’t specify the length of the array in its initial creation.
Dim myArray() As String
Now before you can use the array to store elements you will need to redefine it with a length to do this you will need to use the ReDim command.
ReDim myArray(2) As String
If we need to increase the size again we would simply use ReDim again, however this will cause any existing data to be lost. If you want to keep all current elements in the dynamic you will need to use the Preserve keyword.
ReDim Preserve myArray(5) As String
Array Utility/Helper Functions
If you have a delimited String that you want to break up based on a character the Split function is what you will want to use. It takes a String and a delimiter and returns an Array containing sub strings between the delimiter.
Dim userArray() As String Dim userNames As String nameArray= "Matthew,Doug,Sarah,Jill" userArray = Split( nameArray, "," ) ' The generated array would contain 4 elements userArray 'Matthew userArray 'Doug userArray 'Sarah userArray 'Jill
Conversely you may find that you want to take an array and concatenate the elements with some value between the elements. In this case you would use the Join method. If you don’t want any delimiter between the values you simply don’t input a 2nd parameter and empty string will be used by default.
Dim userArray(3) As String Dim userNames As String userArray = Matthew userArray = Doug userArray = Sarah userArray = Jill userNames = Join(userArray, "," ) usernames 'Matthew,Doug,Sarah,Jill
As shown Visual Basics has all the common functionality of arrays in other programming languages the key to remember is that you use parenthesis not square brackets when accessing element indexes.
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