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PROGRAMMING LANGUAGESGeneration and Levels1

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WHATISAPROGRAMMINGLANGUAGE?

A programming language is used to write computerprograms such as

Applications

Utilities

Syntax in which computer programs are written

Allows a programmer or end user to develop thesets of instructions that constitute a computerprogram or software

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PROGRAMMING LANGUAGES

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COMMON PROGRAMMING LANGUAGES

MachineLanguage

AssemblyLanguage

SQL

High levelLanguages

WebDevelopment

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GENERATIONSOF PROGRAMMINGLANGUAGES

1GL or first-generation language was (and still is)machine languageor the level of instructions anddata that the processor is actually given to work on(which in conventional computers is a string of 0s

and 1s).

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DISADVANTAGES

Programs had to be written using binary codesunique to each computer

Programmers had to have detailed knowledge ofthe internal operations of the specific type of CPU

Programming was difficult and error-prone

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2GL or second-generation language is assembler(sometimes called "assembly") language. A typical2GL instruction looks like this:

ADD 12,8

An assembler converts the assembler language statementsinto machine language.

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CONT

Uses symbolic coded instructions which are easierto remember

Programming is simplified - not necessary to knowthe exact storage location of data and instructions

Disadvantage:Unique to specific make of computer

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3GL or third-generation language is a "high-level"programming language, such as PL/I, C, or Java. Javalanguage statements look like this:

public boolean handleEvent (Event evt) {

switch (evt.id) {

case Event.ACTION_EVENT: {

if ("Try me" .equald(evt.arg)) {

A compiler converts the statements of a specific high-levelprogramming language into machine language. (In the case of Java,the output is called bytecode, which is converted into appropriatemachine language by a Java virtual machine that runs as part of anoperating system platform.) A 3GL language requires a considerableamount of programming knowledge.

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HIGH LEVEL LANGUAGE

Third generation of programming languages

COBOL - business applications

BASIC - microcomputers

FORTRAN - scientific and engineering

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ADVANTAGES

Easier to learn and understand

Statements resemble human language or standardmath notations

Less rigid rules, forms and syntax, so potential forerror is reduced

Machine-independent programs

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DISADVANTAGES

Less efficient than assembler language programs

Require a greater amount of computer time fortranslation into machine instructions

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4GL or fourth-generation language is designed tobe closer to natural language than a 3GL language.

Less procedural and more conversational than priorlanguages

Languages for accessing databases are oftendescribed as 4GLs. A 4GL language statementmight look like this:

EXTRACT ALL CUSTOMERS WHERE "PREVIOUS

PURCHASES" TOTAL MORE THAN $1000

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ADVANTAGES

Simplify the programming process

Encourage users and programmers to specifydesired results

Computers determine the sequence of instructionsthat will accomplish those results

Use natural languages that impose no rigidgrammatical rules

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DISADVANTAGES

Less flexible than other languages

Less efficient in terms of processing speeds andamount of storage capacity required

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5GL or fifth-generation language is programming thatuses a visual or graphical development interface tocreate source language that is usually compiled with a

3GL or 4GL language compiler.

Microsoft, Borland, IBM, and other companies make 5GL visualprogramming products for developing applications in Java, forexample. Visual programming allows you to easily envision object-

oriented programming class hierarchies and drag icons to assembleprogram components.

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OBJECT ORIENTED LANGUAGES

Tie data elements and the procedures, or actionsthat will be performed on them, together intoobjects

C++

Java

Visual C#

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ADVANTAGESOF OOP

Easier to use and more efficient for programminggraphics-oriented user interfaces

Programmed objects are reusable

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TRANSLATORS

Assembler-Translates the symbolic instructioncodes of programs written in an assemblerlanguage into machine language instructions

Compiler - Translates (compiles) high-levellanguage statements (source code) to machine

language programs (object code)

Interpreter-Translates and executes eachprogram statement one line at a time, instead of

first producing a complete machine languageprogram, like compilers and assemblers do

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LEVELSOF PROGRAMMING LANGUAGES

High Level

Middle Level

Low Level

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