User Guide

108 Chapter 2: ActionScript Language Reference
Array.length
Availability
Flash Player 5.
Usage
my_array.length:Number
Description
Property; a non-negative integer specifying the number of elements in the array. This property is
automatically updated when new elements are added to the array. When you assign a value to an
array element (for example,
my_array[index] = value), if index is a number, and index+1 is
greater than the
length property, the length property is updated to index+1.
Note: If you assign a value to the length property that is shorter than the existing length, the array will
be truncated.
Example
The following code explains how the length property is updated:
var my_array:Array = new Array();
trace(my_array.length); // initial length is 0
my_array[0] = 'a';
trace(my_array.length); // my_array.length is updated to 1
my_array[1] = 'b';
trace(my_array.length); // my_array.length is updated to 2
my_array[9] = 'c';
trace(my_array.length); // my_array.length is updated to 10
trace(my_array);
// displays:
// a,b,undefined,undefined,undefined,undefined,undefined,undefined,undefined,c
// if the length property is now set to 5, the array will be truncated
my_array.length = 5;
trace(my_array.length); // my_array.length is updated to 5
trace(my_array); // outputs: a,b,undefined,undefined,undefined