Ivor Horton's Beginning Visual C++ 2012

AN EXAMPLE USING FUNCTIONS

You have covered a lot of ground in C++ up to now and a lot on functions in this chapter alone. After wading through a varied menu of language capabilities, it’s not always easy to see how they relate to one another. Now would be a good point to see how some of this goes together to produce something with more meat than a simple demonstration program.

Let’s work through a more realistic example to see how a problem can be broken down into functions. The process involves defining the problem to be solved, analyzing the problem to see how it can be implemented in C++, and, finally, writing the code. The approach here is aimed at illustrating how various functions go together to make up the final result, rather than providing a tutorial on how to develop a program.

Implementing a Calculator

Suppose you need a program that acts as a calculator; not one of these fancy devices with lots of buttons and gizmos designed for those who are easily pleased, but one for people who know where they are going, arithmetically speaking. You can really go for it and enter a calculation from the keyboard as a single arithmetic expression, and have the answer displayed immediately. An example of the sort of thing that you might enter is:

2*3.14159*12.6*12.6 / 2 + 25.2*25.2

To avoid unnecessary complications for the moment, you won’t allow parentheses in the expression and the whole computation must be entered in a single line; however, to allow the user to make the input look ...