Programming

Computers are controlled by sets of instructions called programs. Programs are written by a person called a programmer using special languages called programming languages.

There is a large number of computer languages available for use by programmers. Each language is designed for use in solving particular types of problem and therefore has particular strengths and weaknesses. A system analyst has to decide which language is most appropriate in ach situation. Languages such as C++ are particularly suitable for writing systems programs. These are programs that are used to control the basic functions of a computer system e.g. operating system programs. Languages such as Visual Basic and Pascal are easy to use and are particularly suitable for learning how to program. FORTRAN is designed for solving engineering problems, COBOL for writing business programs, Ada for military purposes, Prolog and LISP for working in artificial intelligence, i.e. an area of computing concerned with developing computer programs that perform tasks that can normally only be done using human intelligence. Logo is particularly suited for use by young children.

Some languages such as HTML and XML are markup languages rather than programming languages i.e. they use tag codes (labels) for marking text for use in programs such as Web browsers. Languages such as Java and Perl have a number of specialized uses including adding features to Internet connections and webpages (hyperlinked documents).

Some expressions from the programming language used in the text in this unit are shown in the table below.

 

Expression	Meaning
\\	remark (a not for the programmer that is not processed)
PRINT	shows the value of a variable on the display screen
CLS	clears the display screen
END	marks the end of a program

Programmers often do some systems analysis as well as writing the program code. Their first task is usually to analyze the problem, so that they can design a system to deal with it. When they have designed a code for a system and tested it, they then have to create documentation, i.e. notes which explain the structure and logical steps of the program for future users and trainers. They have to be involved in the initial training of users, so that they can make changes to the program according to information obtained from the users. They sometimes use diagrams, called flowcharts, to show the sequence of logical steps in a program. Flowcharts have arrowheads to indicate the direction of program flow and special symbols to indicate different functions in the program.

It is very difficult to write a program without any faults. The errors, or bugs as they are commonly known, can be caused by a number of factors, and programs usually have to be debugged, i.e. tested and altered to eliminate all the errors, before they are used.

3 Answer the following questions:

1. Are computers controlled by sets of instructions?

2. Whom are programs written by?

3. What does a programmer use to write a program?

4. What is the first task of programmers?

5. What does documentation to a program contain?

6. Do programmers have to be involved in the initial training of users? What for?

7. What do programmers use to show the sequence of logical steps in a program?

8. Is it easy to write a program without any faults?

9. What does the term “debug” mean?

 

UNIT 20