ActionScript for Flash MX: The Definitive Guide, Second Edition

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Chapter 4

CHAPTER 4

Primitive Datatypes

Primitive data consists of simple characters or keywords, such as the numbers 0, 1, 2,

3, 4, 5, 6, 7, 8, and 9, or the strings “a”, “b”, and “c”. As shown in Chapter 3, the

primitive datatypes supported by ActionScript are number, string, boolean, unde-

fined, and null. In this chapter, we’ll explore how to define, examine, and change

data of each type.

The Number Type

Numbers are used for counting, mathematics, and keeping track of numeric proper-

ties in our movies (such as the current frame of a movie clip or its location on the

Stage). Let’s see how numbers are defined and manipulated in ActionScript.

Integers and Floating-Point Numbers

Most programming languages distinguish between two kinds of numbers: integers

and floating-point numbers. An integer is a whole number that has no fractional com-

ponent. Integers can be positive, negative, or the number 0. Floating-point numbers

(floats for short) can include a fractional value represented after a decimal point, as

in 0.56, 199.99, and 3.14159. So, 1, 34523, –3, 0, and –9999999 are integers, but

223.45 and –0.56 are floats.

Numeric Literals

We learned earlier that a literal is a direct representation of a single, fixed data value.

The number type supports three kinds of literals: integer literals, ...