MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH, Руководство пользователя

Страница: 161 / 830

About statements 161
4. Select Frame 1 of the Timeline, and then type the following ActionScript in the
Actions panel:
var users_ds:mx.data.components.DataSet;
//
users_ds.addItem({name:"Irving", age:34});
users_ds.addItem({name:"Christopher", age:48});
users_ds.addItem({name:"Walter", age:23});
//
users_ds.first();
while (users_ds.hasNext()) {
trace("name:" + users_ds.currentItem["name"] + ", age:" +
users_ds.currentItem["age"]);
users_ds.next();
}
5.
Select Control > Test Movie to test the document.
The following information is displayed in the Output panel:
name:Irving, age:34
name:Christopher, age:48
name:Walter, age:23
For more information, see the
while statement
in the ActionScript 2.0 Language
Reference .
About do..while loops
You can use the
do..while
statement to create the same kind of loop as a
while
loop.
However, the expression is evaluated at the bottom of the code block in a
do..while
loop (it’s
checked after the code block executes), so the loop always runs at least one time. The
statements execute only if the condition evaluates to
true
.
The following code shows a simple example of a
do..while
loop that generates output even
though the condition is not met.
var i:Number = 5;
do {
trace(i);
i++;
} while (i < 5);
// Output: 5
When you use loops, you need to avoid writing infinite loops. If the condition in a
do..while
loop continuously evaluates to
true
, you create an infinite loop that displays a
warning or crashes Flash Player. Use a
for
loop instead if you know how many times you
want to loop. For more information on and examples of
do..while statement
, see the
ActionScript 2.0 Language Reference .