ActionScript for Flash MX: The Definitive Guide, Second Edition

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Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Chapter 11: Arrays

Summing the values of an array’s elements manually isn’t exactly the paragon of

optimized code. Later, we’ll see a much more convenient way to access an array’s

elements sequentially.

Setting an Element’s Value

To set an element’s value, we use arrayName[elementNumber] as the left-hand oper-

and of an assignment expression:

// Make an array

var cities = ["Toronto", "Montreal", "Vancouver", "Waterloo"];

// cities is now: ["Toronto", "Montreal", "Vancouver", "Waterloo"]

// Set the value of the array's first element

// cities becomes ["London", "Montreal", "Vancouver", "Waterloo"]

cities[0] = "London";

// Set the value of the array's fourth element

// cities becomes ["London", "Montreal", "Vancouver", "Hamburg"]

cities[3] = "Hamburg";

// Set the value of the array's third element

// cities becomes ["London", "Montreal", 293.3, "Hamburg"]

cities[2] = 293.3; // Notice that the datatype change is not a problem

Note that we can use any nonnegative numeric expression as the index when setting

an array element:

var i = 1;

// Set the value of element i

// cities becomes ["London", "Prague", 293.3, "Hamburg"]

cities[i] = "Prague";

Determining the Size of an Array

All arrays come with a built-in property named length, which indicates the current

number of elements (including undefined ...