ActionScript for Flash MX: The Definitive Guide, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Chapter 5: Operators

var x = 1;

// Postfix increment: y is set to 1, then x is incremented to 2

var y = x++;

We’ll revisit the increment operators in Chapter 8.

Subtraction

The subtraction operator subtracts the second operand from the first operand. It

takes the general form:

operand1 – operand2

The operands can be any valid expression. If either operand is not of the number

type, and conversion to a number fails, the operation yields

NaN:

234 – 5 // Yields 229

5 – 234 // Yields –229

To determine the absolute (i.e., positive) difference between two numbers, see the

Math.abs() method in the Language Reference.

Decrement

The decrement operator is analogous to the increment operator, but it subtracts 1

from its operand’s current value instead of adding 1. Like increment, decrement has

two general forms, called prefix decrement and postfix decrement, as follows:

––operand // Prefix decrement

operand–– // Postfix decrement

In both forms, it is used to subtract 1 from a variable, array element, or object prop-

erty. Prefix decrement subtracts 1 from

operand and returns the value of operand -1;

postfix decrement subtracts 1 from

operand but returns the value of operand itself,

not

operand -1. As with the increment operators, the form of decrement used mat-

ters only if the operand is part of a larger ...