Computer Languages

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Computer Languages

• Computing

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Machine Code

• The only type of program a computer can run is a
  machine code program.
• which looks like this.

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Low Level Languages

• Low-level languages were developed to make it
  easier for programmers to write and edit programs.

• Each machine code instruction is given a
  mnemonic.

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Assembler

• A Low level language is often called an Assembly
  Language.
• A computer cannot run an Assembly Language
  program.
• An Assembler converts an Assembly Language
  program into machine code then the computer can
  run it.

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Assembly Language

• It takes many instructions to perform simple
  tasks.
• Assembled programs run fast so needed for Eg.
  Games.

..but Assembly language programming is still hard
workso.
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High Level Languages

• A high level language uses recognisable
  instructions closer to English!
• It is easier for programmers to develop and edit
  high level programsand this will mean faster
  program development.
• and fewer bugs!

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Program Translators

• A High level language program need to be
  translated into machine code programs before a
  computer can run it.
• Compilers translate high level language source
  code into executable object code programsthat
  the computer can run.
• Interpreters translate each line of a high level
  language program, running each instruction as it
  does so.

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Examples of High Level Languages

• FORTRAN (FORmula TRANslator) used for
  scientific computing.
• ALGOL (ALGOrithmic Language)
• COBOL (Common Business Orientated Language) used
  for commercial programming.
• BASIC (Beginners All-Purpose Symbolic
  Instruction Code) a learning language.
• PASCAL A well-structured teaching language.
• C, C, C, C - Evolved from Algol.
• JAVA Popular language used for teaching
  programming
• and many, many more..

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High Level Languages

• Scientific languages would have powerful
  mathematical functions, and facilities for high
  precision arithmetic to many decimal places
• Commercial languages would have many data
  processing functions (searching and sorting) and
  filing facilities.

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HTML
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facearial colorredgtRonaldoslt/fontgtlt/tdgt lttd
gtltfont facearial colorwhitegtFirst
Pagelt/fontgtlt/tdgt lt/trgt lttrgt lttdgtltimg
srcc\ronaldo.jpg alignrightgtlt/imggtlt/tdgt lt/t
rgt lt/tablegt lta hrefpage2.htmgtPage 2lt/agt lt/bodygt

• ..stands for HyperText Markup Language.
• .... is used to develop web pages. A web page is
  really a program written in HTML with
  instructions for the web browser telling it how
  to display the page.
• Hyperlinks can be used for navigation between web
  pages.
• Multimedia objects can be embedded in a web page.

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Special-Purpose Languages

• Some languages have a special purpose such as
• PROLOG for Artificial Intelligence
• GASP - for Simulation
• OCCAM for parallel processing systems.
• ADA for programming embedded systems.

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Procedural Languages

• A sequence of instructions is executed.
• use variables, program control (loops etc) and
  subroutines.
• Examples PASCAL, BASIC, FORTRAN, COBOL, ALGOL.

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Non-Procedural Languages

• A set of facts
• and a set of rules, from which information is
  deduced.

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Example (Non-procedural Language)PROLOG

• Facts
• Parent(Tom, Bob)
• Parent(Pam,Bob)
• Male(Tom)
• ..and a set of rules
• Father(X,Y)
• parent(X,Y)
• Male(X)
• Brother(X,Y)
• parent(Z,X)
• Parent(Z,Y)
• Male(X)

and a query which is answered by applying the
facts and rules ? father(who,Bob) who Tom
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Object Oriented Programming Languages (OOPs)

• Objects have Properties and Methods.
• Properties can be set initially or at run-time.
• Methods are the things the object can do.

Examples of OOPs C, VB .NET, JAVA, PHP, PYTHON)
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Fundamentals of an OOP

• A Class defines the properties and methods of
  something.A DOG is a class Properties may
  include Colour, Breed, No of Legs, etc Methods
  may be Bark, Eat, Run, Sit, etc..
• An Object is a particular instance of a
  Class.LASSIE is an instance of a DOG
• A Sub-Class may be defined such as SPANIEL that
  INHERITS the methods and properties of the Class
  DOG.

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Visual Languages

• Visual Languages allow the programmer to
  manipulate objects visually on a form, and set
  their layout and properties.
• Often used to create Microsoft Windows
  Applications.
• Examples Visual Basic, Visual C, Delphi.

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ALL programming languages must have

• International Standards.
• Difficult to create because of different hardware
  and software manufacturers.
• An unambiguous syntax.
• There should never be two different ways for a
  computer to interpret an instruction.