Ch 1 Object-Oriented Programming

8/13/2019 Ch 1 Object-Oriented Programming

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An Introduction to Programming Using Alice

Object-Oriented

Programming


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Object-Oriented Programming

An algor i thm is a step-by-step process.

A com puter program is a step-by-step set of

instructions for a computer.

Every computer program is an algorithm.

Algorithms have a long history in science,

technology, engineering and math.


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Early computers were

far less complex than

computers are today.

Their memories were

smaller and their programs

were much simpler.


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They usually executed onlyone program at a time.


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Modern computers are

smaller, but far more

complex than earlycomputers.

The can execute many

programs at the same time.


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Computer scientists have

introduced the notion of

objects and object-or iented programm ingto

help manage the growing

complexity of modern

computers.


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An objectis anything that can be represented by

data in a computers memory and manipulated by

a computer program.






a computer program.

Numbers






a computer program.

Text






a computer program.

Pictures






a computer program.

Sound






a computer program.

Video




An object is anything that can be represented by data.




Anobject can be something

in the physical world or

even just an abstract idea.

An airplane, forexample, is

a physical object that can

be manipulated by a

computer.




Anobject can be something

in the physical world or

even just an abstract idea.

A bank transaction is an

example of an object that

is not physical.




To a computer, an object is

simply something that can

be represented by data in

the computers memory and

manipulated by computer

programs.


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Computer programs

implement algorithms that

manipulate the data.

In object-oriented

programming, the programs

that manipulate theproperties of an object are

the objects methods.




We can think of an object

as a collection of properties

and the methods that are

used to manipulate those

properties.

Properties

Methods


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A classis a group of

objects with the same

properties and the same

methods.


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Each copy of an object

from a particular class iscalled an instance of

the object.


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The act of creating a

new instance of anobject is called

instantiation.


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A class can be thought

of as a blueprint forinstances of an object.


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A I t d ti t P i U i Ali


The same terminology

is used in most object-

oriented programming

languages.

Object

Instance

Property

MethodInstantiation

Class

State

Ch 1 Object-Oriented Programming

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