Tuesday, October 4, 2011

Computer Programming and Programming Languages

A computer program is a series of instructions that directs a computer to perform tasks, Created by a programmer using a programming language. 

Machine language is classified as a first generation language - 1GN.
Assembly Language is the second generation language - 2GN.

Programmer writes instructions using symbolic instruction codes. A source program contains the code to be converted to machine language.

3GN languages are allot more easier to program in. Which can then be converted to 1GN or 2GN languages.

In a procedural language, the programmer writes instructions that tell the comptuer what to accomplish and how to do it.

Third-Generation Language (3GL)

A third generation can compile and translate an entire program before executing it. An interpreter converts an executes one code statement at a time.

Source Program + Data > Interpreter > Results (EXE - The compiled program)

Object-Orientated Programming Languages and Program Development Tools

An object-orientated programming language allows programmers the ability to reuse and modify existing objects.

Other advantages include; objects can be reused, works well in a RAD environment, Programmers create applications faster.

Microsoft .NET Framework allows many types of programs to run onthe internet or an internal business network, as well as computers and mobile devices.

Features include: CLR (Common Language Runtime), Classes.

Visual Studio is a Microsoft suite of programs developed as tools to assist with programming.

A 4GL Language is a non-procedural language that enables users and programmers to run a query with using procedures. Examples of these are MySQL, SQL and CFM.

Web Page Development is just a markup language. It is a very limited language.

HTML is a special formatting language that programmers use to format documents for display on the Web. XHTML is a markup language that allows Web sites to be displayed more easily on mobile devices.

XML is a way for Web developers to create customized tags and use predefined tags to display content appropriately on various devices. WML is a subset of XML and is used to design pages for microbrowsers.

Two applications of XML are RSS 2.0 and ATOM.

Programmers write scripts, applets, servlets, or ActiveX controls using a variety of languages.

Javascript, Perl, PHP.

Web Page Development

Web 1.0 - Looking at the content or change the webpage.
Web 2.0 - Provides a mean to change or modify the content in some way. Creating a Blog, Wiki, Facebook, Bebo, Twitter etc.
Web 3.0 - Data driven.

Web page Authoring Software can create sophisticated Web pages that include images, video, audio animation etc.

Other authoring tools include, ToolBook Director which are designed for different platforms.

When creating a Program - Step One - Analyze Requirements

It is writted to tbe the solution to a problem or an answer to an opportunity.

To initiate a program development, programmer must: Reviews the requirements, meets with the systems analyst and users, identifies input, processing and output.

Input                   |                     Processing                         |               Output
The input var             The processing that this step does             What's the answer...

Step Two - Design Solution

In structured design, the programmer typically begins with a general design and moves toward a more detailed design. Programmers use a hierarchy template.

Object-Orientated (OO) design the programmer packages the data and the program into a single object. Encapsulation.

The selection control is an action to take, based on a certain condition. If-then-else, case, etc.

Pseudo Code is another way of going about Designing the Solution - It is a condensed form of English to convey program logic.

Step Three - Validate the Design

Check for logic errors by checking your Pseudo Code.

Step Four - Implement Design

Implementation of the design includes using a program development tool that assists the programmer by:
  • Generating or providing some or all code. 
  • Writing the code that translates the design into a computer program. 
  • Creating the user interface. 
Extreme programming is a strategy where programmers immediately begin coding and testing solutions as soon as requirements are defined. 

Step Five - Test the Solution

Step Six - Documentation of the Solution

The Pseudo Code can be used to review the program.

System Development

System Development can follow three general guidelines. Groups activities or tasks into phases, involve users, define standards.

What is System Development

System Development should involve representatives from each department in which the proposed system will use.

Who initiates a System Development Project - A user may request a new or modified system, Organisations may want to improve hardware, software or other technology. Situations beyond an organisations control might require a change.

Analysis Phase - Consists of two major parts, conduction research and a full solution is developed.


Design Phase - Is a prototype proof of concept that can be used while the full system is being created still.

Implementation Phase - Various tests should be performed on the new system.

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