CISC 124: Introduction To Moodle vs. Web Site Computing Science II - - PowerPoint PPT Presentation

CISC 124, winter 2014, set 1: introduction 1

CISC 124: Introduction To Computing Science II

instructor: Margaret Lamb course web site: www.cs.queensu.ca/home/cisc124

• ffice: Goodwin 554
• ffice hour this week:

Monday 12-1 Wednesday 2-3 Friday 1-2 vote on Moodle for office hours for rest of term

CISC 124, winter 2014, set 1: introduction 2

Moodle vs. Web Site

Web site on CISC server: http://cs.queensu.ca/home/cisc124/index_w14.html Option 1:

• Read web site for basic information

(content/admin)

• Go to Moodle for extras (forums, etc.)

Option 2:

• Use Moodle as front page (links to everything in

web page)

CISC 124, winter 2014, set 1: introduction 3

Reading Assignment For Wednesday

Read administrative info on web site. Pay special attention to syllabus & bring questions to class on Wednesday. Look at schedule, tell me about any problems with quiz dates

CISC 124, winter 2014, set 1: introduction 4

Reading Assignment For Friday

Chapters 1-3 of the Java text. See web site for sections you may skip. Complete Moodle survey about the reading by noon on Friday. I expect you to:

• Do readings as assigned.
• Complete surveys to tell me your reactions.

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Marking Scheme

quizzes (best 3 of 4): 50% final exam: 34% assignments (best 7 of 8): 10% participation: 6% (questionnaires, forums, in-class activities) You must pass quizzes+final exam to pass the course.

CISC 124, winter 2014, set 1: introduction 6

Academic Integrity

• Everything you hand in must be your own work

(assignments, quizzes, final)

• Exception: may do assignments in group (2-4 students),

all names must be on submission

• Why?
• It's only fair!
• Queen's reputation, value of degrees

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• Gaining more programming experience
• Learning about Object-Oriented Programming (OOP)

Language used: Java

What's This Course About?

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Predecessors:

• CPL, BCPL (1960s)
• B (1969)
• C (early 1970s)
• C++ (1980s, object-oriented)

A Brief History of Java

Java:

• Sun Microsystems (now part of Oracle)
• first public version 1995
• design team led by Jim Gosling (Canadian!)
• initial target: embedded systems
• goals included: portability & reliability
• 1994: World Wide Web!

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Computers speak machine language – binary codes for very simple operations. Very cumbersome for humans to read and write! No standard: every make/model has its own language.

Computer Languages & Translation

Assembly Language:

• Symbolic form of machine language
• Easier for humans to handle
• Simple program ("assembler") translates to machine

language

• Still involves a lot of detail
• Still machine-dependent

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Idea: Languages that are closer to the way we think: logic, data types, mathematical notation

High-Level Languages

Advantages:

• Easier/faster to read & write
• Can be translated into different machine languages

Disadvantages:

• Needs a complicated translation program
• Not always completely portable – depends on

language design and translation programs

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• Interpreter (Python, Basic)
• Compiler (C, C++)
• Hybrid Approach (Java)

Translation Methods

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Reads & executes a program in a high-level language.

• Read a line or statement
• Figure out what it means
• Make it happen
• Repeat!

Interpreter

Python Program Python Interpreter input to program

• utput of

program

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Reads a program in a high-level language. Creates an equivalent program in machine language.

Compiler

C Program C Compiler input to program machine language program

Step 1: Step 2:

machine language program

• utput of

program

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Pros & Cons

Need For Extra Program:

• Compiler: Program is compiled once. You don't need the

compiler to run the program.

• Interpreter: You need the interpreter each time you run the

program. Efficiency: Interpreted languages traditionally viewed as less

• efficient. Changing with clever new technology ("just in time"

compilation). Portability:

• Compilers: You need to write a compiler for every

"platform" (hardware & OS)

• Interpreters: Not always necessary

Both: Great care is needed to make a language truly portable (same results on all kinds of computers)

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JVM = Java Virtual Machine A hypothetical computer "Bytecode": the machine language of the JVM. Designed to suit the Java language, still pretty low-level.

Java's Hybrid Approach

Java Program (.java) Java Compiler bytecode program (.class)

Step 1: (once) Step 2: (every time you run the program)

bytecode program (.class) Java Interpreter Program Output Program Input