Online Computer Programming Classes

Unit 1: Principles of Programming

Introduction
In this unit you will learn some general terms related to computer programming such as languages and algorithms. You will be familiar with these terms after reading this unit. The importance of an algorithm in a programming language can be realised in lesson 2. Chronological development of different languages and their uses are described in this unit. A general rule of writing algorithm is also described here.

Lesson 1: Objectives of Computer Programming

1.1 Learning Objective
On completion of this lesson you will learn

i) programming and programming language

ii)  why programming is popular

iii) history of programming.

1.2 Definition of Programming
Programming is writing instructions for a machine specially a computer. The machine which works differently according to the instructions given to it is called a programmable machine. The jobs of these machines are not fixed. We can change the working plan of the machine by changing the instructions or programs. Computers are machines that can understand the instruction and work properly according to the instructions given.
In short, programming means step by step instructions for solving a problem by computer.

1.3 What is a Language?
The instruction given to the computer must have a particular format. Computers are unable to understand human language. There are several levels of format or language which a computer can understand. The interest of understanding computer languages increases day by day. History of computer languages is as old as computer science. This is described in the following sections.

1.4 Different Types of Language

1.4.1 Low level languages
In old days computers were very large and were not much reliable. Programming was done by switches and there was no facility to use the program. This approach of computer programming was completely a hardware technology. Next the approach of machine language comes up. In this approach instruction set of the computer consists of some numerical digits. This instruction set is used to build up a program. This code is difficult to understand for human beings. Next assembly language was introduced. In assembly language the numerical codes are replaced by suitable names which are understandable. This has made programming easier.

1.4.2 High level languages
This type of languages are like English language. But this is more structured. Actually this type of languages support mathematical notations used in arithmetic expressions. There are some special rules for writing programs in high level languages. Pascal, C, C++, Mathematica, Java, Math lab etc. Ada are all high level languages. High level languages are easy to write, compile and suitable for error correction.

1.4.3 Fourth Generation Languages
Scientists are trying to develop computer languages like human languages. They have not been successful but may be successful in near future. These languages have greater built-in facility such as database query, searching, sorting and interfacing. FoxPro, Cobol, Visual Basic, MS Access, Oracle Forms and Reports, SQL systems make use of such programs or languages. These are also known as the Fourth Generation Languages (4GL).

1.5 Purpose of Programming
There are several purposes of programming. These are discussed below.

1.5.1 Computer program for automated systems
Different offices need different system. So a ready made software is not enough for this purpose. Special programs should be written for office automation. These softwares may be used for accounting, payroll systems, machine control, industrial control, billing system of electricity, telephone and water, result processing of examination etc. It is important to develop these softwares properly because the output of the whole system depends on the output of the computer system.

1.5.2 Developing the system
Demand increases day by day. So new systems should be introduced. This is done by introducing new programs and new versions of programs. Sometimes new machines come up with extra facilities.
Existing systems may not support these facilities. At that time developed programs are necessary for better utilisation of machines.

1.5.3 Scientific research
Scientific research requires computers for implementing the theory into practice. Huge numbers of calculations are required for this purpose. Only a computer program can help the scientists out. There are some programs which are useful for scientific calculations. For example, FORTRAN, C++, Mathematica, Math Lab. Simulation is also very necessary for research, which can be performed using simulation packages.

1.5.4 Development of programming languages
This is one of the main purposes of programming. High level languages are made from low level languages. Even top versions of high level languages are programmed by low version of high level languages. This idea of developing programming tool is called boot strapping. That is the objective of programming is to make the programs easier so that a layman can run his machine without the help of a programmer. This is actually the future trend of programming. Now the programmers are not concerned about the data structures and algorithms used. The compiler will use the proper data structure and efficient algorithm to solve the problem.

1.5.5 Object of this programming course
This course of programming is not all in all in computer programming. We have discussed some aspects of high level languages and then discussion on Pascal programming language will be found in subsequent lessons. This is actually an introductory course. Extra ordinary features of Pascal have been omitted from the book for reduction of complexity. Having learnt all the lessons, one will not only know the structure of Pascal but also be capable of writing short programs. This will develop the conception of programming within a very short time. The people who are totally ignorant about computers may get help from this course.