Lecture 19 / Chapter 13
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
General Items:
•
•
•
•
•
•
Lecture 19 / Chapter 13
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
Computer Program
Lab? Ok?
Read the extra credits
Need to come to class
Have a quiz / no books / use notes -> What is the big idea
School is almost over
•
•
•
•
A series of instructions that direct a computer to perform tasks
Such as? Who is the programmer?
Programming language is a series of rules for writing the instructions
There are hundreds of computer programs – need-based!
Programming language
Reading Materials:
- Two basic types: Low- and high-level programming languages
o Low-level: Programming language that is machine-dependent
Must be run on specific machines
o High-level: Language that is machine-independent
Can be run on different types of machines
•
Miscellaneous:
Programming Language
Low Level
Machine
Language
Remember:
Ultimately, everything
must be converted to the
machine language!
F.Farahmand
Lecture 19 / Chapter 13
1 / 12
File: lec14chap13f04.doc
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
Categories of programming languages
- Machine language
o Only language computer understands directly
- Assembly language
o Instructions made up of symbolic instruction codes
o Assembler converts the source code to the machine language
- Third-generation language
o Uses a series of English-like words to write instructions
- Procedural language -> Programming instructions to tell computer what
to accomplish and how to do it
o Compiler:
Separate program that generates programming list (consists of
errors)
Program that converts entire source program into machine
language before executing it
o Object program
Used for execution later
o Interpreter
Program that translates and executes one program code
statement at a time
Does not produce an object
Source
Code:
Assembly/3
F.Farahmand
Compiler
3 / 12
F.Farahmand
Lecture 19 / Chapter 13
High Level
Assembly
Language
Procedural
Nonprocedural
Object Oriented
2 / 12
COSC1300/ITSC 1401/BCIS 1405
File: lec14chap13f04.doc
12/5/2004
o Nonprocedural language -> Programmer specifies only what the
program should accomplish; it does not explain how
- Forth-generation language
o Syntax is closer to human language than that of a 3GL
o SQL and report generator are examples
- Fifth-generation language
o Provides visual or graphical interface for creating source code
o Visual Basic.NET is an example
- Common procedural programming languages
o BASIC
Designed for use as a simple, interactive problem-solving
language
Beginner's All-purpose Symbolic Instruction Code
o COBOL
o C (Changed B to C!)
Object
Program
File: lec14chap13f04.doc
F.Farahmand
4 / 12
File: lec14chap13f04.doc
Lecture 19 / Chapter 13
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
Lecture 19 / Chapter 13
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
Object-oriented (OO) approach
o The structured programming does not explain how to keep the data and
program together
o Eliminates redundant programming
o No more spaghetti code
o Programmer can package data and program (or procedure) into a single
unit, called an object (uses the OO approach)
o OOP is event-driven
o Checks for and responds to set of events
o C++ is a complete object-oriented language
OO Programming languages
Hundreds of programming languages exist – They are different in flexibility,
user interface, and functionality
o C++ : Classes and events
o Java and Java applets: Small Java program that runs inside another
program such as a Web browser
o Visual Programming Language
Windows-based application that assists programmers in
developing event-driven Windows-based applications
Fifth – generation language
• Allows drop and drag of objects
• Easy to use
Examples:
• Visual Basic
• Visual Studio/Visual C++/Visual C# .NET
o Run over the Internet
o Easier programming development
o Suitable for large/small – scale applications
F.Farahmand
Lecture 19 / Chapter 13
5 / 12
COSC1300/ITSC 1401/BCIS 1405
File: lec14chap13f04.doc
12/5/2004
Web page program development tools
o Tools used to create web pages
o Adding special effects and forms to a Web page
Examples: Cookies, Shopping cards, Games, and many other
multimedia effects
Script: Interpreted program that runs on client
Applet: Also usually runs on client, but is compiled – runs
faster than script
Servlet: Applet that runs on server
ActiveX control: Small program that runs on client
o HTML
Hypertext Markup Language – set of special codes used to
create web pageNot a programming language – Page formatting language
Uses tags an must be kept as an ASCII file
o Dynamic HTML:
Allows you to include more graphics and interactivity on Web
page (pointing to a text changes the shape)
Animations, Interactions, Scroll bar, pop-up windows
o XML: eXtensible Markup Language
Allows Web page developers to create tags that describe data
passed to a client so client, rather than server, can process
data – different platforms can display the same XML
o XHTML: eXtensible HTML Includes features of HTML and XML
o WML Wireless Markup Language
Allows Web page developers to design pages specifically for
micro-browsers
Uses the wireless application protocol (WAP)
o Web page authoring:
Dreamweaver MX, FrontPage, Flash
F.Farahmand
7 / 12
File: lec14chap13f04.doc
F.Farahmand
Lecture 19 / Chapter 13
6 / 12
COSC1300/ITSC 1401/BCIS 1405
File: lec14chap13f04.doc
12/5/2004
o Common Gateway Interface Program (CGI)
Used for sending and receiving information over the web
Basic Idea:
• Resides in the server
• When a search is requested the it is sent to the CGI
program
• The CGI contacts the database and requests the
information
• The CGI receives the information from the database and
shows it in HTML format and it is sent to the web
browser
F.Farahmand
8 / 12
File: lec14chap13f04.doc
Lecture 19 / Chapter 13
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
System development life cycle
9 / 12
Lecture 19 / Chapter 13
o
o
o
o
F.Farahmand
COSC1300/ITSC 1401/BCIS 1405
File: lec14chap13f04.doc
12/5/2004
• Flowchart (Graphically shows logic in a solution
algorithm)
• Pseudocode (Uses condensed form of English to convey
program logic)
Code programs
Translating solution algorithm into a programming language
Entering programming language code into the computer
Test programs
Goal is to ensure program runs correctly and is error free Three types of errors
• Syntax
• Logic
• Run time
Debugging: Process of locating and correcting syntax and logic
errors in program
Formalize solution
Programmer performs two activities
• Reviews program code
• Reviews documentation
Maintain program
Identify errors
Identify enhancements
Involves modifying existing programs to improve their
functionality
11 / 12
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
Program development life cycle
- A system is a set of components that interact to achieve a common goal
- System development life cycle generally has 5 phases:
o Planning
o Analysis
o Design
o Implementation
o Support
F.Farahmand
Lecture 19 / Chapter 13
File: lec14chap13f04.doc
- A computer program is a set of instructions that directs computer to
perform tasks
- A programming language is a set of words, symbols, and codes that
enables a programmer to communicate instructions to a computer
- PDLC is a steps followed to build computer programs
o Analyze problem
Review program specifications package
Meet with systems analyst and users
Identify each program’s input, output, and processing
components
o Design problems
Grouping program activities to modules (top-down design)
Providing a solution algorithm for each phase and testing it
(structured design)
Top-down design: Focuses on what program should do
Structured design: Focuses on how to build program based on
requirements (Creating a hierarchical chart)
• Uses a technique that builds all program logic by
combining three control structures:
o Sequence control structure (Input, Process, Output)
o Section control structure (if-then-else)
o Repetition control structure (do-while)
Writing proper programs:
• No-dead codes
• No infinite loops
• One entry point
• One exist point (no spaghetti code – not structured)
Using design tools (graphical or written description of each
module)
F.Farahmand
Lecture 19 / Chapter 13
10 / 12
File: lec14chap13f04.doc
COSC1300/ITSC 1401/BCIS 1405
12/5/2004
QUIZ
What is a computer program?
Why do we use Object-oriented programming language?
Name 3 programming languages.
Name 2 web page development techniques.
What is HTML?
F.Farahmand
12 / 12
File: lec14chap13f04.doc