Ndu06 typesof language


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Ndu06 typesof language

  1. 1. ND Unit 06Types of Programming Language
  2. 2. This session will cover: Procedural languages Object-orientated programming Visual languages Mark-up languages Scripting languages To Pass assignment 1 you must describe 4 different types of language [P1]
  3. 3. Procedural Languages Early Windows programs used these The program controls what happens not the user The task is completed based on user input Tasks are broken into a number of stages known as procedures or subroutines
  4. 4. Procedural Languages  Each procedure does a specific part of the task  For example a procedure might open a file, read in a number or multiply 2 numbers  Examples are C, Fortran, Pascal, and Basic
  5. 5. Object-orientated programming (OOP) Is relatively new and not used until the 1990’s when programs got more complex The program is broken down into objects, not lists of instructions Each object can perform tasks and communicate with other objects The object can be thought of as a small machine with a set job
  6. 6. Object-orientated Example A company’s personnel records program would have an employee object The employee object would have features such as Forename Surname and date of birth – we call these attributes The object would also have actions such as join company, leave company, change details – we call these methods
  7. 7. Object-orientated programming (OOP)  Unlike procedural programming, the programmer does not need to know the code which is ‘behind’ each object making it work  They only need to know the attributes and methods of each object and how to make it interact with other objects  They then use the objects as ‘building blocks’ to make the program do what they want it to  Examples languages capable of OO are Java, C# and VB.NET
  8. 8. Visual Programming Languages  These are used to create software which has a graphical user interface (GUI), such as Windows programs  VP languages have procedural features but also have OO capabilities  Examples of VP languages are Visual Basic.NET and Visual C++
  9. 9. Visual Programming Languages  VP design has 2 stages  First the programmer designs the GUI, placing objects such as textboxes, buttons and labels onto a form  Then they write the code which gives the functionality to the program
  10. 10. Markup Languages  A markup language combines text and extra information about the text  This extra information is in the form of tags  Tags control the structure or presentation of the text – should it be large or small font, blue, green, bold or underlined?  The programmer can also insert images, hyperlinks and tables into the text using tags
  11. 11. Markup Languages The best-known markup example is Hypertext Markup Language (HTML), used on the World Wide Web Example: <title>Home Page</title> <style type="text/css" media="screen"> @import "stylesheets/public.css"; body { background-color: white }; </style> Another example is XML (Extensible Markup Language) which allows users to write their own tags
  12. 12. Scripting languages  Scripting languages can be typed in directly from a keyboard  Some are used to execute a series of commands that would otherwise have to be typed in via a keyboard / mouse  These can be used to control the operating system and are known as a shell script language  Examples are VBScript and Windows Powershell
  13. 13. Scripting languages  Others allow users to write short, simple, programs  Often the language used is specific to each application such as the macro languages used in Access or Excel  Script can also be used to write functions that are included in HTML pages to do tasks which can’t be done with HTML alone  An example of this is JavaScript
  14. 14. Which language to use depends on:  Organisational policy – your company may be ‘tied’ to Microsoft or Macintosh  Will it work on the hardware already used?  Does it do what we need it to?  Are current staff trained in its use?  Is it reliable? Important for safety-critical systems!  Costs of developing and maintaining programs  Will it be expandable in future?