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 2: Variables

conversion cannot be performed). By comparison, VB.NET allows the programmer

to decide whether the compiler should enforce strict typing. Strict typing may seem

cumbersome, but it can prevent the errors that unsuspecting programmers may

encounter due to automatic and dynamic typing, which we’ll consider in the follow-

ing sections.

Automatic Value Conversion

In some contexts, ActionScript expects a specific type of data. If we use a variable

whose value does not match the expected type, the interpreter attempts to convert

the data to the necessary type. For example, if we use a text variable where a number

is needed, the interpreter will try to convert the variable’s text value to a numeric

value for the sake of the current operation. In Example 2-2,

z is set to 2. Why?

Because the subtraction operator expects a number, the value of y is converted from

the string “4” to the number 4, which is subtracted from 6 (the value of

x), yielding

the result 2.

Conversely, if we use a numeric variable where a string is expected, the interpreter

attempts to convert the number to a string. In Example 2-3,

z is set to the string

“64”, not the number 10. Why? Because the second operand in the expression x + y

is a string. Therefore, the

+ operator performs string concatenation instead ...