ActionScript for Flash MX: The Definitive Guide, Second Edition

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Chapter 7: Conditionals

words, an else statement is perfect for depicting a mutually exclusive decision; one

code block will be executed and the other will not.

Here’s some code to demonstrate:

var lastName = "Grossman";

var gender = "male";

if (gender = = "male") {

trace("Good morning, Mr. " + lastName + ".");

} else {

trace("Good morning, Ms. " + lastName + ".");

}

The else clause often acts as the backup plan of an if statement. Recall our password-

protected web site example. If the password is correct, we let the user enter the site;

otherwise, we display an error message. Here’s some code we can use to perform the

password check (assume that

userName and password are the user’s entries and that

validUser and correctPassword are the correct login values):

if (userName = = validUser && password = = correctPassword) {

this.gotoAndPlay("intro");

} else {

this.gotoAndStop("loginError");

}

The Conditional Operator

Simple two-part conditional statements can be expressed conveniently with the con-

ditional operator (

?:). The conditional operator has three operands, which you’ll rec-

ognize as analogous to the components of an if-else statement series:

condition ? expression1 : expression2;

In a conditional operation, if condition is true, expression1 is evaluated and

returned. Otherwise,