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while 1005
while
Availability
Flash Player 4.
Usage
while( condition ) {
statement(s) ;
}
Parameters
condition
An expression that evaluates to
true
or
false
.
statement(s)
The instructions to execute if the condition evaluates to
true
.
Returns
Nothing.
Description
Statement; evaluates a condition and if the condition evaluates to
true
, runs a statement or series
of statements before looping back to evaluate the condition again. After the condition evaluates to
false
, the statement or series of statements is skipped and the loop ends.
The
while
statement performs the following series of steps. Each repetition of steps 1 through 4
is called an iteration of the loop. The
condition
is retested at the beginning of each iteration, as
shown in the following steps:
1.
The expression
condition
is evaluated.
2.
If
condition
evaluates to
true
or a value that converts to the Boolean value
true
, such as a
nonzero number, go to step 3.
Otherwise, the
while
statement is completed and execution resumes at the next statement
after the
while
loop.
3.
Run the statement block
statement(s)
.
4.
Go to step 1.
Looping is commonly used to perform an action while a counter variable is less than a specified
value. At the end of each loop, the counter is incremented until the specified value is reached. At
that point, the
condition
is no longer
true
, and the loop ends.
The curly braces (
{}
) used to enclose the block of statements to be executed by the
while
statement are not necessary if only one statement will execute.
Example
In the following example, the
while
statement is used to test an expression. When the value of
i
is less than 20, the value of
i
is traced. When the condition is no longer
true
, the loop exits.
var i:Number = 0;
while (i<20) {
trace(i);
CHAPTER 2
ActionScript Language Reference