ActionScript for Flash MX: The Definitive Guide, Second Edition

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

Arithmetic Operators

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and “5” are converted to the numbers 3 and 5 before the multiplication is per-

formed. The

+ operator, however, presents a special case: when used with at least

one string operand, it performs string concatenation, not mathematical addition.

If an attempt to convert a nonnumeric operand to a number fails, the operand is set

to the special numeric value

NaN. This results in the entire operation yielding NaN.

Refer to Table 3-1 for details on numeric conversion.

Addition

The addition operator returns the sum of its two operands:

operand1 + operand2

In order to return a meaningful mathematical result, the operands of + should be

expressions that yield a numeric value, such as:

234 + 5 // Returns 239

(2 * 3 * 4) + 5 // Returns 29

The addition operator is unique among the arithmetic operators in that if one or

both of its operands are strings, it performs as a string concatenation. Refer to “Join-

ing Strings Together” in Chapter 4.

Increment

A handy variation on addition, the increment operator accepts a single operand and

simply adds 1 to its current value. Increment has two general forms, called prefix

increment and postfix increment, as follows:

++operand // Prefix increment

operand++ // Postfix increment

In both forms, increment adds 1 to a variable, array element, or ...