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.

44

|

Chapter 2: Variables

Changing and Retrieving Variable Values

After we create a variable, we can assign and reassign its value as often as we like, as

shown in Example 2-1.

Notice that we changed the variable

x’s datatype from numeric to text data by sim-

ply assigning it a value of the desired type. Some programming languages don’t allow

the datatype of a variable to change, but ActionScript does.

Of course, creating variables and assigning values to them is useless if you can’t

retrieve the values later. To retrieve a variable’s value, simply use the variable’s name

wherever you want its value to be used. Anytime a variable’s name appears (except in

a declaration or on the left side of an assignment statement), the name is converted

to the variable’s value.

Here are some examples. Note that

_x is a built-in property representing a movie clip’s

horizontal position with no relation to the variable named

x used in preceding exam-

ples (see the “Variable Naming Styles” sidebar in Chapter 1, and see MovieClip._x in

the Language Reference).

newX = oldX + 5; // Set newX to the value of oldX plus 5

ball._x = newX; // Set the horizontal position of the

// ball movie clip to the value of newX

trace(firstName); // Display the value of firstName in the Output window

Note that in the expression ball._x ...