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Accessing all of the items within a Dynamic Array Since we don't know, at the time we write the program how many elements a Dynamic Array will contain, we can't use the 'Brute Force' method we used earlier. One way to deal with the variable nature of a Dynamic Array is to use the LBound and Ubound Visual Basic functions. LBound returns the Lower Bound of an Array, and Ubound returns the Upper Bound of an Array. Therefore, to display all of the values in an array on our form, we can execute this code… For x = LBound(strLetters) To UBound(strLetters) Form1.Print strLetters(x) Next x The beauty of this code is that no matter how many letters are in our file (or our Array), this code is 'smart enough' to handle it.
We can take this code on step further by using the Visual Basic For…Each statement to 'loop' through the elements of the Array. For those of you not familiar with it, the For…Each statement, in conjunction with an Object variable, can be used to 'loop' through the elements of a Visual Basic Collection---but it can also be used to loop through the elements of an Array, like this… Dim y As Variant For Each y In strLetters Form1.Print y Next In this code, the variable y is an Object Variable (and it MUST be declared as a Variant). Y is used, by the For…Each statement as a placeholder to the value of the element in the Array. Here's a final look at the code … Dim strLetters() As String Dim x As Integer Open "C:\LETTERS.TXT" For Input As #1 Do While Not EOF(1) ReDim Preserve strLetters(x) Input #1, strLetters(x) x = x + 1 Loop Close #1 Dim y As Variant For Each y In strLetters Form1.Print y Next and for good measure, let's modify the contents of our file
and run the program one more time to be sure that it works…
Summary I hope you've enjoyed this refresher on Arrays, and that you will find the use of the For…Each statement a valuable technique. |
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