Ivor Horton's Beginning Visual C++® 2005

Chapter 3. Decisions and Loops

In this chapter, you will look at how to add decision-making capabilities to your C++ programs. You'll also learn how to make your programs repeat a set of actions until a specific condition is met. This will enable you to handle variable amounts of input, as well as make validity checks on the data that you read in. You will also be able to write programs that can adapt their actions depending on the input data and to deal with problems where logic is fundamental to the solution. By the end of this chapter, you will have learned:

• How to compare data values

• How to alter the sequence of program execution based on the result

• How to apply logical operators and expressions

• How to deal with multiple choice situations

• How to write and use loops in your programs

I'll start with one of the most powerful and fundamental tools in programming: the ability to compare variables and expressions with other variables and expressions and, based on the outcome, execute one set of statements or another.

Comparing Values

Unless you want to make decisions on a whim, you need a mechanism for comparing things. This involves some new operators called relational operators. Because all information in your computer is ultimately represented by numerical values (in the last chapter you saw how character information is represented by numeric codes), comparing numerical values is the essence of practically all decision making. You have six fundamental operators for comparing two values ...