Programming Excel with VBA and .NET

Types of Add-ins

From a user’s perspective, an add-in is a file that you load by selecting Tools → Add-ins from within Excel. Add-ins extend Excel in some way and usually display a toolbar or add menu items as a way to get at their features.

Table 22-1 lists the add-ins that ship with Excel. There also are many free sample add-ins available by searching http://office.microsoft.com/ for “Excel add-ins.”

Table 22-1. Add-ins installed with Excel

Add-in	Provides	Adds menu item
Analysis ToolPak	Advanced functions for financial and scientific data analysis	Tools → Data Analysis
Analysis ToolPak VBA	Support for using the Analysis Toolpak functions from Visual Basic	None
Conditional Sum Wizard	Formulas to sum data in lists	Tools → Conditional Sum
Euro Currency Tools	Conversion and formatting for the Euro currency	Tools → Euro Conversion
Internet Assistant VBA	Support for saving worksheets as HTML from Visual Basic	None
Lookup Wizard	Wizard to help create formulas to find value in a range	Tools → Lookup
Solver	What-if analysis of data	Tools → Solver

From a developer’s perspective, add-ins are Excel applications without a worksheet interface. Instead, add-ins act on objects in the currently loaded workbook. There are two main types of add-ins:

• Code-only add-ins provide user-defined functions that can be used from Excel formulas or within Visual Basic.

• Visual add-ins provide wizards or toolbars to help users performs specific actions.

Some add-ins combine these two types. ...