XL97: How to Programmatically Create a Collection

• Microsoft Excel 97 for Windows

SUMMARY

New programming functionality in Microsoft Excel 97 allows you to create a collection. A collection is a predefined object that stores groups of related objects. A collection makes it easier to work with the object group. For example, you can use a For Each looping structure to loop through the collection. Each time the macro executes the loop it references a different object in the collection until all objects in the collection are referenced once.

This article includes a sample Visual Basic for Applications macro that creates and references a collection.

MORE INFORMATION

Microsoft provides examples of Visual Basic for Applications procedures for illustration only, without warranty either expressed or implied, including, but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. The Visual Basic procedures in this article are provided 'as is' and Microsoft does not guarantee that they can be used in all situations. While Microsoft support engineers can help explain the functionality of a particular macro, they will not modify these examples to provide added functionality, nor will they help you construct macros to meet your specific needs. If you have limited programming experience, you may want to consult one of the Microsoft Solution Providers. Solution Providers offer a wide range of fee-based services, including creating custom macros. For more information about Microsoft Solution Providers, call Microsoft Customer Information Service at (800) 426-9400.

In general, declare an object as a new collection to create the collection. After you create the Collection object, add items to the collection using the Add method or remove items using the Remove method.

1. Create a new workbook and start the Visual Basic Editor (press ALT+F11).

2. On the Insert menu, click Class Module.

3. In the class module, type the following declaration:

   Public EmployeeName As String

   You typically use a public variable in a class modules to define properties for the class.

4. If the Properties window is not visible, click Properties on the View menu.

5. If the Project Explorer window is not visible, click Project Explorer on the view menu.

6. In the Project Explorer, click the class module you inserted in the project in step 2.

7. In the Properties window, change the (Name) property of the class module to "EmpClass" (without the quotation marks).

8. On the Insert menu, click Module.

9. In this module, type the following code:

          Sub MyCollection()
      
              Dim employees As New Collection   'Create the collection object.
              Dim num As Integer
      
              num = 0    'Counter for number of employees added to the 
                         'collection.
      
              Do
                  Dim employee As New EmpClass    'Create new instance of the
                                                  'EmpClass class.
                  num = num + 1
      
                  newname = InputBox("Enter new employee name" & Chr(13) _
                      & "or press Cancel to see list of employees.")
      
                  If newname <> "" Then   'You did not press Cancel.
      
                      employee.EmployeeName = newname
                      employees.Add Item:=employee, key:=CStr(num)
      
                      Set employee = Nothing    'Clear the current reference
                                                'in preparation for next one.
      
                  End If
      
              Loop Until newname = ""  'You pressed Cancel.
      
              For Each x In employees
                  MsgBox x.EmployeeName 'Display the employee name.
              Next
      
              MsgBox employees.Count  'Current number of employees in 
   

   
           For Each x In employees
               employees.Remove 1   'Remove each employee from the 

           Next
   
           MsgBox employees.Count 'Display a count of zero because
                                  'all employees were removed from the
                                  'collection.
   
       End Sub