PROGRAMMING LANGUAGES

 

 

Low Level Language 

Each language instruction equates to a single machine instruction
Machine language
Assembly language

Machine Dependent Language

A language that runs on only one type of computer

 

High Level Language 

Each language instruction typically equates to multiple machine instructions

Machine Independent Language

A language that can run on many different types of computers

Machine Language

Uses binary vectors (1s and 0s) that are interpreted as computer instructions or data
Only language that computer will directly recognize

Assembly Language

Uses mnemonics, or symbolic instruction codes
Each mnemonic corresponds to a machine language instructions
May also use symbolic addresses, or variables

Procedural Languages

Sequence of programming instructions
Tells computer what to do step-by-step
High level languages
BASIC, COBOL, Pascal, C

Compiler

Converts a high level language source program into machine language before it can be executed.

Interpreter

Converts a single high level source program statement into machine language, executes it, then moves on to the next statement.

Assembler

Converts an assembly language source program into machine language before it can be executed.

 

Events

An action to which the program responds
Mouse click, keypress, saving a file, moving the focus
An OOP language is event driven

Visual Programming Languages

Provide a Visual Programming Environment
Developer drag and drop objects to create programs
Used for Rapid Application Development (RAD)
Visual Studio.NET includes Visual Basic.NET, Visual C#

Nonprocedural Languages

Contain English-like instructions that retrieve data or files from a database
RPG (Report Program Generator)

4GLs

Fourth Generation Languages
Nonprocedural Language that allows access to data in a database
SQL

Application Generator

Program that creates source code or machine code from a specification
Consists of a report writer, forms, and menu generator

Macros

Series of statements that instruct an application how to complete a task
May be recorded
May be written
Good for recording repetitive tasks

CGI Scripts

Common Gateway Interface
A set of standards that define how a web server communicates with outside sources
Script, Servlet, Applet,  ActiveX Control

Script

An interpreted program that typically runs on the client
Server side scripts run on servers
UNIX scripting languages, SED, AWK
JavaScript
VBScript
PERL

Applet

A compiled program that runs on the client

Servlet

A compiled program that runs on a server

Java

A compiled object oriented programming language
Used to write stand-alone applications
Also used to write applets and servlets

PERL

An interpreted scripting language
Used to add functionality to websites by inserting HTML and other code into web pages.