INTRODUCTION OF PROGRAMING

It is the intent of this manual to provide an introduction to computer programming, and to the programming language, BASIC (Beginners All-Purpose Symbolic Instruction Code). BASIC is a popular programming language, especially for new programmers and casual computer users. Its conversational nature makes communicating with computers natural, simple, and straightforward. Its use of near English words and mathematical expressions gives the coding a familiar appearance. Also, its original design, to teach the casual user how to program, makes it a good language to learn first. For those of you with computer operations experience, this course is intended to provide a transition from operations into programming. It will intro-duce concepts of programming that apply to other languages as well as BASIC. For those of you with programming experience, it will provide a review of programming concepts and introduce the capabilities of BASIC and its syntax. For those not in data processing, who have a computer available, it will pro-vide an introduction to a programming language available on most computers. When you complete the course, you should understand the capabilities and syntax of the BASIC language and be able to write a program.

OVERVIEW OF PROGRAMMING
Before learning to program in the language, BASIC, it is helpful to establish some context for the productive part of the entire programming effort. This context comprises the understanding and agreement that there are four funda-mental and discrete steps involved in solving a problem on a computer. The four steps are:

1. State, analyze, and define the problem.

2. Develop the program logic and prepare a program flowchart or decision table.


3. Code the program, prepare the code in machine readable form, prepare test data, and perform debug and test runs.


4. Complete the documentation and prepare operator procedures for implementation and production.


Programming can be complicated, and advance preparation is required before you can actually start to write or code the program. The first two steps, problem understanding/definition and flowcharting, fall into the advance planning phase of programming. It is important at this point to develop

Figure 1-1.—Evolution of a Program.

correct habits and procedures, since this will prevent later difficulties in pro-gram preparation.

Whether you are working with a systems analyst, a customer, or solving a problem of your own, it is extremely important that you have a thorough understanding of the problem.

Every aspect of the problem must be defined:

. What is the problem?

What information (or data) is needed?

. Where and how will the information be obtained?

. What is the desired output?

Starting with only a portion of the information, or an incomplete definition, will result in having to constantly alter what has been done to accommodate the additional facts as they become available. It is easier and more efficient to begin programming after all of the necessary information is understood.