1. Programming Concepts and Languages
Chapter 11 – Computers: Understanding Technology

2. Terminology
A program is a set of instructions telling a computer how to perform a task
The program is written in a programming language
The programming language instructions are referred to as source code and the act of writing source code as coding

3. Programming Languages
Fewer words and symbols and simpler syntax than natural language
Can either be low-level or high-level
Elements are variables, executable statements, decision statements, looping
Algorithm (complete list of steps for solving a problem) often written in pseudocode (high level language meant to describe steps) and then programmer writes in programming language

4. Reusable Code
Certain problems or tasks recur in programming so it is desirable to avoid “reinventing the wheel” when this occurs
Subroutine or function to do certain tasks – the idea is that one needs to understand what inputs it needs and what outputs it produces but not how it works

5. Program Execution
Some computer languages require a compiler, a computer program which translates the programming language source code into machine code
Other languages are executed via interpreters

6. Documentation Tools Flowcharts – Visual representation of algorithm
Comments – Messages in programs that explain source code to later readers

7. Programming Errors
Syntax errors
Logic errors
Runtime errors

8. Programming Languages
Assembly languages – uses symbols and words to represent elements of machine language – 1 assembly language statement generally produces 1 machine code statement
COBOL (1960) – business applications language
RPG – Report Program Generator (IBM AS/400 mainframe)

9. Programming Languages (cont.)
FORTRAN (1957) – dominated math and scientific programming
BASIC – interpreted language, originally developed as teaching tool
Visual Basic (VB) – language of choice for developing software prototypes
Visual Basic.Net (ITP 112, ITP 212)
C (ITP 130, ITP 230) – elements of both BASIC and assembly language, runs fast

10. Programming Languages (cont.)
C++ (ITP 132, ITP 232) - superset of C
C# (ITP 136) - derived from C++ and Java
Java – (ITP 120, ITP 220, ITP 246) - cross-platform flexibility; when used in web pages, called applets, but this is rarely done now; web use is primarily server-side

11. Scripting Languages JavaScript (ITD 210, ITP 140, ITP 225) VBScript
Perl
Cold Fusion
Active Server Pages (ASP)
ASP.Net (ITP 244)
PHP (ITP 225)

12. Markup Languages HTML – Hypertext Markup Language (ITD 110)
XHTML – Extensible Markup Language
XML – Extensible Markup Languages
WML – Wireless Markup Language