Many analysts credit the early success of Visual Basic to custom controls. It's easy to see why—custom controls mean that you aren't limited to one vendor for all your programming tools. You can choose the best tools from a free and competitive marketplace.
With Visual Basic, you can create your own custom controls (called ActiveX controls). ActiveX controls written in Visual Basic look and behave just like controls written in C. In fact, you can distribute them to your C-programming friends for use in Microsoft Visual C++.
ActiveX controls can be used just about everywhere: on Web pages viewed by Internet Explorer; in Microsoft Excel and Microsoft Word documents; in Microsoft Access and Visual FoxPro database applications; and, of course, in Visual Basic, Microsoft Visual C++, and Microsoft Visual J++.
This chapter shows you how to create ActiveX controls and describes the programming issues that are unique to these controls. The sample code presented in this chapter is available on the companion CD-ROM.