Chapter 9 Interactive Multimedia Authoring with Flash - Introduction to Programming

nostalgicisolatedΛογισμικό & κατασκευή λογ/κού

4 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

87 εμφανίσεις

Chapter 9

Interactive Multimedia Authoring with
Flash
-

Introduction to Programming


“Computers and Creativity”

Richard D. Webster, COSC 109 Instructor

Office: 7800 York Road, Room 422 | Phone:


(410) 704
-
2424

e
-
mail:
webster@towson.edu

109 website:


http://pages.towson.edu/webster/109/

1

2

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




3

More Common Terms


Computer Programming Languages


are for writing instructions that can be followed by
a computer


IDE


stands for:

I
ntegrated
D
evelopment
E
nvironment


refers to:


the software in which you are developing an
application


for example, Adobe Flash, Microsoft Visual Studio

4

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.

5

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

6

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 $

7

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.

8

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.

9

Case Sensitivity of Variable Names


score

and
Score

are different


number

and
nuMBer

are different

10

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
.

11

Assigning a Value to a Variable

General Syntax:

variableName

=

value or
expression
;



Examples:

score = 10;

letterGrade = "A";

sum = a + b;


12

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
;


13

Declaring a Variable

Examples:

var score:int;



var score:int = 0;


14

Data Types

Basic Data Types in Actionscript

int

uint

Number

String

Boolean

MovieClip

Object

Null

void


15

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.

16

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

17

if Statements


if


if...else


if...else if


Nested if statements

18

if

General Syntax:

if (
logical expression(s)
)

{


statement(s)

}

19

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

if

Example:

if (score > 600)

{


grade = "pass";

}

20

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";


21

If statements and looping


Both if statements and Loops can be used to
make a program execute
nonsequentially
.

22

if...else

General Syntax:

if (
logical expression(s)
)

{


statement(s)

}

else

{


statement(s)

}

23

if...else

Example:

if (score > 60)

{


grade = "pass";

}

else

{


grade = "fail";

}

24

if...else if

General Syntax:

if (
logical expression(s)
)

{


statement(s)

}

else if (
logical expression(s)
)

{


statement(s)

}

...

else if (
logical expression(s)
)

{


statement(s)

}

else

{



statement(s)

}

25

if...else if

Example:

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";

}

26

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.

27

if...else if

Example:

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";

}

28

Suppose score = 85.

if...else if

Example:

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";

}

29

Suppose score = 85.

First check: (score > 90).


(85 > 90) is false!

Logical Operators

&&

AND

||

OR


!

NOT

30

Logical AND:
&&

logicalExpression1

&&

logicalExpression2


true

: only when
both

logicalExpression1

and
logicalExpression2

are
true


false

: when
either

logicalExpression1

or
logicalExpression2

is
false

31

Logical OR:
||

logicalExpression1

||

logicalExpression2


true

: when
either

logicalExpression1

or
logicalExpression2

is
true


false

: only when
both

logicalExpression1

and
logicalExpression2

is
false

32

Logical NOT:
!

!
logicalExpression1


true

: when
logicalExpression1

is
false


false

: when
logicalExpression1

is
true

33

Examples

Example 1

if (age < 40
&&

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

Example 2

if (age < 40
||

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

34

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

Examples

Example 1

if (age < 40
&&

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

Example 2

if (age < 40
||

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

35

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

Examples

Example 1

if (age < 40
&&

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

Example 2

if (age < 40
||

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

36

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

Examples

Example 1

if (age < 40
&&

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

Example 2

if (age < 40
||

weight < 150)

{


group = 2;

}

else

{


group = 3;

}

37

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

Examples

Sum =
addTogether
(2,5);


By examining the statement above you should
be able to infer that
addTogether
()


Returns a value, and, Takes arguments

38

f
unctions and procedures

(see text pages 305
-
307)



function: block of code that forms a discrete
unit with a name;


Procedure: very similar to functions, excerpt
that they do not return values. Otherwise,
both functions and procedures can take
paremeters
.


39