The Waite Group's C++ Primer Plus, Third Edition

Floating-Point Numbers

Now that you have seen the complete line of C++ integer types, let's look at the floating-point types, which compose the second major group of fundamental C++ types. These numbers let you represent numbers with fractional parts, such as the gas mileage of an M1 tank (0.56 MPG). They also provide a much greater range in values. If a number is too large to be represented as type long, for example, the number of stars in our galaxy (an estimated 400,000,000,000), you can use one of the floating-point types.

With floating-point types, you can represent numbers like 2.5 and 3.14159 and 122442.32—that is, numbers with a fractional part. A computer stores such values in two parts. One part represents a value, and the other part ...