Data types

In ActionScript, there are many data types that you can use as the data type of the variables you create. Some of these can be thought of as "simple" or "fundamental" data types:

String: a textual value, like a name or the text of a book chapter
Numeric: ActionScript 3.0 includes three specific data types for numeric data:
- Number: any numeric value, including values with or without a fraction
- int: an integer (a whole number without a fraction)
- uint: an "unsigned" integer, meaning a whole number that can't be negative
Boolean: a true-or-false value, such as whether a switch is on or whether two values are equal

The simple data types represent a single piece of information: for example, a single number or a single sequence of text. However, the majority of the data types defined in ActionScript could be described as complex data types, because they represent a set of values grouped together. For example, a variable with the data type Date represents a single value--a moment in time. Nevertheless, that date value is actually represented as several values: the day, month, year, hours, minutes, seconds, and so on, all of which are individual numbers. So while we think of a date as a single value (and we can treat it as a single value by creating a Date variable), internally the computer thinks of it as a group of several values that, put together, define a single date.

Most of the built-in data types, as well as data types defined by programmers, are complex data types. Some of the complex data types you might recognize are:

MovieClip: a movie clip symbol
TextField: a dynamic or input text field
SimpleButton: a button symbol
Date: information about a single moment in time (a date and time)

Two words that are often used as synonyms for data type are class and object. A class is simply the definition of a data type--it's like a template for all objects of the data type, like saying "all variables of the Example data type have these characteristics: A, B, and C." An object, on the other hand, is just an actual instance of a class; a variable whose data type is MovieClip could be described as a MovieClip object. The following are different ways of saying the same thing:

The data type of the variable myVariable is Number.
The variable myVariable is a Number instance.
The variable myVariable is a Number object.
The variable myVariable is an instance of the Number class.

Flash CS3

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