ActionScript: The Definitive Guide

Assigning Variables

Now comes the fun part—putting some data into our variables. If you’re still playing along with the bank analogy, this is the “deposit money into our account” step. To assign a variable a value, we use:

               variableName = value;

where variableName is the name of a variable, and value is the data we’re assigning to that variable. Here’s an applied example:

bookTitle = "ActionScript: The Definitive Guide";

On the left side of the equal sign, the word bookTitle is the variable’s name (its identifier). On the right side of the equal sign, the phrase “ActionScript: The Definitive Guide” is the variable’s value —the datum you’re depositing. The equal sign itself is called the assignment operator. It tells Flash that you want to assign (i.e., deposit) whatever is on the right of the equal sign to the variable shown on the left. If the variable on the left doesn’t exist yet, Flash creates it (though relying on the interpreter to implicitly create variables isn’t recommended).

Here are two more variable assignment examples:

speed = 25;
output = "thank you";

The first example assigns the integer 25 to the variable speed, showing that variables can contain numbers as well as text. We’ll see shortly that they can contain other kinds of data as well. The second example assigns the text “thank you” to the variable output. Notice that we use straight double quotation marks (” “) to delimit a text string in ActionScript.

Now let’s look at a slightly more complicated example that assigns ...