HOW TO: Expose an Array Through a User-Defined Property

This step-by-step article describes how to create a property that exposes an array in Microsoft Visual Basic 6.0. In Visual Basic 6.0, the Property Get statement and Property Let statement do not support arrays. However, you can create a property that exposes an array if the array is wrapped in a variant type variable.

Requirements

The following list outlines the recommended hardware, software, network infrastructure, and service packs that are required:

• Microsoft Visual Basic 6.0

This article assumes that you are familiar with Visual Basic 6.0 programming.

Step-By-Step Example

1. Start Visual Basic 6.0, and then create a new Standard EXE project.
   
   By default, Form1 is added to the project.
2. On the Project menu, click Add Class Module.
   
   An Add Class Module dialog box appears on the screen.
3. Click to select Class Module, and then click Open.
   
   By default, Class1 is added to the project.
4. In the Properties window, change the class name to MyCalendar.
5. Paste the following code in MyCalendar:

   Option Explicit
   
   Private tempArray As Variant
   
   Public Property Get DatesSelected() As Variant
      DatesSelected = tempArray
   End Property
   
   Public Property Let DatesSelected(ByVal dates As Variant)
      tempArray = dates
   End Property
   

6. In the Project Explorer window, double-click Form1.
7. Add a CommandButton to Form1.
8. In the Properties window, change the caption to Property Let.
9. Add another CommandButton to Form1.
10. In the Properties window, change the caption to Property Get.
11. In the Project Explorer window, right-click Form1, and then click View Code.
12. Paste the following code in Form1:

    Option Explicit
    
    Dim objMyCal As New MyCalendar
    
    Private Sub Command1_Click()
       Dim i As Integer
       
       Dim arrDate(5) As Date 
       
       ' Creates the array containing six elements.
       ' Do not specify the dimensions for the array.
       For i = 0 To 5
          arrDate(i) = Int(Now) + i
       Next i
       
       ' Assign the array to the property.
       objMyCal.DatesSelected = arrDate
       
       MsgBox ("An array of Dates is assigned to property Let")
    End Sub
    
    Private Sub Command2_Click()
       Dim i As Integer
       Dim upper As Long
       Dim lower As Long
    
       Dim arrMyDates() As Date  ' Dynamic array
       
       ' Get the array from the property.
       arrMyDates = objMyCal.DatesSelected
        
       ' Determine the bounds of the array.
    
       lower = LBound(arrMyDates)
       upper = UBound(arrMyDates)
    
       For i = lower To upper
          MsgBox (arrMyDates(i))
       Next i
    
    End Sub
    

13. On the File menu, click Save Project to save the project.
14. On the Run menu, click Start to run the application.

Verify That It Works

1. After you run the application, a form with the Property Let CommandButton control and the Property Get CommandButton control appears on the screen.
   
   Click Property Let to assign values to the DatesSelected property.
   
   You receive the following message:

   An array of dates is assigned to property Let

   Click OK.
2. Click Property Get to retrieve the dates that the Property Let procedure assigns to the array that the property exposes.
   
   Each of the six dates in the array is displayed in a series of message boxes.

For more information, visit the following MSDN Web sites: