Chapter 9 Interactive Multimedia Authoring with Flash Introduction to Programming 1.

Chapter 9Interactive Multimedia Authoring with Flash

Introduction to Programming

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Some Common Terms

• Writing code– means entering the code– is part of the process of creating the computer

program• Running code, executing code

– refers to the process by which the computer carries out the instructions in a computer program

• Compiling– refers to the process of assembling code into a format

suitable for the computer to execute the instructions

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More Common Terms

• Computer Programming Languages– are for writing instructions that can be followed by

a computer• IDE

– stands for:Integrated Development Environment

– refers to:• the software in which you are developing an application• for example, Adobe Flash, Microsoft Visual Studio

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Programming Languages

low level

high level Programming languages that look more like human language.Easy for human to read and write, but require more "translation" behind the scenes to be understandable to the computer.e.g. C++, Java, FORTRAN

lowest level:Machine language: a programming language that communicates with a computer through 0's and 1's

Assembly language

Multimedia authoring scripting languages, such as Flash Actionscript and Director Lingo are often the highest level.

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Scripting Languages• Examples: Flash ActionScript, Director Lingo, Javascript

• Very-high-level programming languages

• Advantage: easier for non-programmer to learn because the syntax and keywords are close to human languages

• Disadvantages:– Not as full-fledged as programming languages such as C++,

Java, and FORTRAN– Don't have the features to let the programmer to control

low level details, such as memory allocation

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Flash Actionscript

• a scripting language • getting full-fledged• based on the same standard as Javascript

• Actionscript 1.0, 2.0, 3.0

Easiest to learn.

Has stricter rules than 1.0.

The newest version of ActionScript.More difficult than the other two versions.This is what we will be using in this course.

Syntax• prescribes the ways in which statements must be written in

order for them to be understood by the computer

• like the rules of grammar and punctuation in human languages, but these rules must be followed precisely in computer programming

• for examples, for ActionScript:– case sensitive– each statement ends with a semi-colon(;)– the naming of variables and functions has to start with a letter ,

_ or $

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Variables

• Purpose:to store values that can be updated and retrieved at runtime

• Data is stored in memory as bits.• Variable lets you refer, by name, to the data's

memory location stored.

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Variable Naming

• can contain a number, a letter, underscore (_), or dollar sign ($)

• cannot begin with a number• in this course, variables always begin with a letter• cannot be a keyword• look up Actionscript 3.0 Language Reference in

Help for all the keywords• If the word turns blue in your code window, it

means it is a keyword.

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Case Sensitivity of Variable Names

• score and Score are different• number and nuMBer are different

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Assigning a Value to a Variable

• Means giving a value to a variable

• The statement that assigns a value to a variable is called an assignment statement.

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Assigning a Value to a Variable

General Syntax:variableName = value or expression;

Examples:

score = 10;letterGrade = "A";sum = a + b;

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Declaring a Variable

• Before you use a variable or assigning a value to a variable, you need to declare the variable.

• General Syntax:Two ways to declare a variable:– Declare without assigning a value:var variableName:dataType;

– Declare and assign a value:var variableName:dataType = value or expression;

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Declaring a Variable

Examples:var score:int; var score:int = 0;

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Data Types

Basic Data Types in ActionscriptintuintNumberStringBooleanMovieClipObjectNullvoid

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How a Program Runs

• A program is written as a sequence of statements as instructions.

• The program executes the instructions sequentially--one instruction after the other, in the order in which they appear in the code.

• Use control structures to make nonsequential execution of the instructions.

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Types of Control Structures

• Loop– A set of statements is executed repeatedly until a

certain condition is reached– Will be covered in Chapter 11

• Conditional– A set of statements is executed only if some

conditions are met– if statements and switch statements

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if Statements

• if• if...else• if...else if• Nested if statements

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if

General Syntax:if (logical expression(s)){statement(s)

}

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The statements grouped within the curly braces are called the block statements.

if

Example:if (score > 600){grade = "pass";

}

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if

• If there is only one statement to be executed, the curly braces are optional.

• Examples:if (score > 60)grade = "pass";

The statement may be on a single line:if (score > 60) grade = "pass";

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if...else

General Syntax:if (logical expression(s)){statement(s)

}else{statement(s)

}22

if...else

Example:if (score > 60){grade = "pass";

}else{grade = "fail";

}23

if...else ifGeneral Syntax:if (logical expression(s)){

statement(s)}else if (logical expression(s)){

statement(s)}...else if (logical expression(s)){

statement(s)}else{

statement(s)}

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if...else ifExample:if (score > 90){

grade = "A";}else if (score > 80){

grade = "B";}else if (score > 70){

grade = "C";}else if (score > 60){

grade = "D";}else{

grade = "F";}

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if...else if

• The conditions are checked one at a time sequentially.

• Once a condition is found to be true, the statement(s) for that condition will be executed and the rest of the conditions in the if . . . else if statements group will not be checked.

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if...else ifExample:if (score > 90){

grade = "A";}else if (score > 80){

grade = "B";}else if (score > 70){

grade = "C";}else if (score > 60){

grade = "D";}else{

grade = "F";}

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Suppose score = 85.

if...else ifExample:if (score > 90){

grade = "A";}else if (score > 80){

grade = "B";}else if (score > 70){

grade = "C";}else if (score > 60){

grade = "D";}else{

grade = "F";}

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Suppose score = 85.First check: (score > 90).

(85 > 90) is false!

Logical Operators

&& AND|| OR

! NOT

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Logical AND: &&

logicalExpression1 && logicalExpression2

true : only when both logicalExpression1 and logicalExpression2 are true

false : when either logicalExpression1 or logicalExpression2 is false

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Logical OR: ||

logicalExpression1 || logicalExpression2

true : when either logicalExpression1 or logicalExpression2 is true

false : only when both logicalExpression1 and logicalExpression2 is false

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Logical NOT: !

!logicalExpression1

true : when logicalExpression1 is false

false : when logicalExpression1 is true

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Examples

Example 1if (age < 40 && weight < 150)

{group = 2;

}else{group = 3;

}

Example 2if (age < 40 || weight < 150)

{group = 2;

}else{group = 3;

}

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Which statement will be executed in these examples when age = 38 and weight = 145?

Examples

Example 1if (age < 40 && weight < 150)

{group = 2;

}else{group = 3;

}

Example 2if (age < 40 || weight < 150)

{group = 2;

}else{group = 3;

}

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Which statement will be executed in these examples when age = 38 and weight = 157?

Examples

Example 1if (age < 40 && weight < 150)

{group = 2;

}else{group = 3;

}

Example 2if (age < 40 || weight < 150)

{group = 2;

}else{group = 3;

}

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Which statement will be executed in these examples when age = 46 and weight = 145?

Examples

Example 1if (age < 40 && weight < 150)

{group = 2;

}else{group = 3;

}

Example 2if (age < 40 || weight < 150)

{group = 2;

}else{group = 3;

}

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Which statement will be executed in these examples when age = 46 and weight = 157?