CS0007: Introductory Programming

1
CS0007Introductory Programming

• George Novacky
• novacky_at_cs.pitt.edu
• http//courseweb.pitt.edu

2
What is a program?

• A program is a sequence of instructions that
• tells the computer what to do
• tells another human being what you want the
  computer to do
• More formally, a program implements an algorithm.
• Algorithm a finite set of well-defined
  instructions for accomplishing some task
• 
  Wikipedia

3
Program Tasks

• Programs are written for various kinds of tasks
  (not mutually exclusive)
• solve a problem
• create a simulation
• create a game
• produce an animation

4
What is a language?

• A system for communicating.
• Written languages use symbols (that is,
  characters) to build words.
• Parts of Language
• Vocabulary The entire set of words in the
  language.
• Syntax and grammar The ways in which the words
  can be meaningfully combined
• Semantics The actual meaning of words and
  combinations of words
• 
  Java Vocabulary

5
Computer Languages

• Human languages are natural languages.
• Computers are not sophisticated enough to
  understand natural languages.
• In mathematics, logic and computer science, a
  formal language is a set of finite-length words
  (i.e. character strings) drawn from some finite
  alphabet, with carefully defined vocabulary,
  syntax, and semantics
• There are many different kinds of computer
  languages, including machine languages,
  programming languages, and fourth-generation
  languages.

6
Learning to write a program

• A program is written using a programming
  language
• We will learn to write programs using two
  languages
• Alice
• Java

7
Object Oriented Programming

• Different programming languages support different
  styles of programming
• In object-oriented programming, programmers can
  think of a program as instructions that tell
  interacting objects what to do
• An object is a model of some artifact (product of
  civilization) that can interact with other objects

8
Kinds of Animations

• Two kinds of animations
• Movie
• Passive user watches the animation
• What Alice Can Do
• LightDemo
• Octopus
• Interactive
• Active user clicks on mouse, types a key on
  keyboard
• Actions of user are called events
• Flight Simulator
• Skater

9
Objects

• An "object" is a model of an artifact
• and can be identified as unique from other
  things
• there can be multiple objects that are similar,
  but still unique
• How is an object unique?
• has a name
• has properties
• width, height, color, location
• can perform actions (methods)
• associated actions it can perform
• tasks it can carry out

10
Object Parts

• Objects may be composed of parts (which are also
  objects)

11
Class

• A class defines a particular kind of object
• Objects are categorized into classes
• Each object is
• an instance of the class.
• All objects in a class have similar properties
  and generally can perform the same tasks.

12
Galleries

• Classes (3D models) are found in the galleries
• Local gallery (installed with the software)
• Minimum or complete options
• CD Gallery (only if CD is in the machine)
• Web gallery

13
Before next class

• Activity
• Launch Alice on your computer and run some of the
  example worlds.
• Homework
• Read Alice Chapter 1.1 and pages 73 - 74 for a
  brief introduction to objects