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7.2. The else Statement

With a lone if statement, we can cause a single code block to be optionally executed. By adding an else clause, we can choose which of two code blocks should be executed. Syntactically, an else statement is an extension of an if statement:

if (condition) {
  substatements1
} else {
  substatements2
}

where condition may be any valid expression. substatements1 will be executed if condition is true; substatements2 will be executed if condition is false. In other words, an else statement is perfect for depicting a mutually exclusive decision; one code block will be executed and the other will not.

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 could 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) {
  gotoAndPlay("intro");
} else {
  gotoAndStop("loginError");
}


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