Beginning Programming with C++ For Dummies®

Chapter 6. if I Could Make My Own Decisions

In This Chapter

• Defining character variables and constants

• Encoding characters

• Declaring a string

• Outputting characters to the console

Making decisions is a part of the everyday world. Should I get a drink now or wait for the commercial? Should I take this highway exit to go to the bathroom or else wait for the next? Should I take another step or stop and smell the roses? If I am hungry or I need gas, then I should stop at the convenience store. If it is a weekend and I feel like it, then I can sleep in. See what I mean?

An assistant, even a stupid one, has to be able to make at least rudimentary decisions. Consider the Tire Changing Language in Chapter 1. Even there, the program had to be able to test for the presence of a lug nut to avoid waving a wrench around uselessly in space over an empty bolt, thereby wasting everyone's time.

All computer languages provide some type of decision-making capability. In C++, this is handled primarily by the if statement.

The if Statement

The format of the if statement is straightforward:

if (m > n)    // if m is greater than n...
{
              // ...then do this stuff
}

When encountering if, C++ first executes the logical expression contained within the parentheses. In this case, the program evaluates the conditional expression "is m greater than n." If the expression is true, that is, if m truly is greater than n, then control passes to the first statement after the { and continues from there. If the logical expression is ...