Faster Smarter Beginning Programming

Example: Writing a Tape Calculator

This chapter has touched upon quite a few different concepts. Presenting a single example that uses all these concepts yet avoids any concepts from future chapters is a practical impossibility. As a result, this example concentrates mainly on illustrating Dim and If statements. Literals, of course, are ubiquitous. Examples in later chapters will duly illustrate arrays and loops.

Figure 3-1 shows the example program running. As you can see, it’s another calculator like the one in Chapter 2. This one, however, has both Add and Subtract buttons, a tape that shows a history of what you entered, and a Clear button. Also, if you try to add or subtract something that isn’t a number, this calculator displays a dialog ...