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"); }
The Conditional Operator
Simple
two-part conditional statements can be
expressed conveniently with the conditional operator
(?:
). The conditional operator has three operands, ...
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