3GL Program Design
We write computer programs in order to solve the kind of problems which can be solved by computer systems. For example, managing large databases, calculating and processing payrolls, maintaining medical records systems.
For all of these data-processing problems or scenario's there are some fairly well-defined steps in arriving at a working system:
What the course attempts to do:
This course introduces some tools and techniques which can be used in steps 3 and 4 and concentrates on designing programs which will be written in Third Generation Computer Programming Languages known generally as 3GL's. This course should provide a good foundation for a first computer programming course using a 3GL. Even if you don't intend going on to be a computer programmer you will find some useful techniques in this course that will enhance your problem-solving skills.
You don't need any special computer skills to complete this course and every effort is made to explain new or unfamiliar terms. You will find many worked examples and questions for you to attempt.
You will need a computer which can run Netscape or Internet Explorer, this course hypertext material and pen and paper.
Apart from the obvious personal achievement of completing a rewarding and challenging study this course will:
I estimate that it should take twenty to forty hours of study to complete all the material in this course. If you have a background in computing or computer programming you will probably take even less time but remember time is not that important, the important thing is to absorb and understand what you are studying.
1. Computer programs - the introduction
2. Algorithms - a definition and the different ways of specifying algorithms
3. Software Development Life Cycle - SDLC - the stages in the life cycle of the software system
4. Step-Form algorithms - the simplest form of algorithm and trace tables
5. Pseudocode - somewhere between human language and 3GL
6. More work with loops and sequence
7. Dealing with errors and more work with decisions and loops
8. Flowcharts - simple, concise and accurate
9. Nassi-Schneiderman diagrams - a variation on flow-charts
In each lesson you will find a number of objectives, things like this:
In the complete course there are about forty or so objectives and they are stated in terms of something that you should be able to do. If someone was going to determine how much you knew about designing 3GL computer programs these objectives would be a useful way to frame questions that you could be asked. If you were to be hired by someone to design programs then these objectives represent the kinds of skills you need to be able to practice and the nature of the knowledge you need to have.
There are nine lessons and mostly the lessons are fairly cohesive, that is they tend to stay within the topic of the lesson. The lessons should build on each other, you shouldn't find a concept in one lesson that requires knowledge or a skill which appears in a later lesson. Most of the lessons have questions that you should answer and exercises that you should do. The questions and exercises are intended to test your learning of the lesson and to give you the opportunity to practice your new skills and knowledge - the things outlined in the objectives. The questions and exercises are for your benefit, if you are doing the course then you need to know how well you are doing.
Now you have some idea of the shape of the course, how do you tackle it? The key to completing a course like this is disciplined time management. My estimate of the time it should take to complete the course is twenty to forty hours. That includes reading and digesting the lessons, doing the exercises and answering the questions. You don't have to be a genius or a computer whiz but you must be committed to finishing the course
Skim read through the material, that is quickly read through and get a feel for what is in it. While you skim through make a note on pencil and paper of how long it takes to skim each lesson and the exercises and questions.
Work out the ratios of times. For example if it takes a total of one hour to skim through the whole course and you spend 15 minutes skimming lesson 5 then it is reasonable to plan on spending 25% of your total time on lesson 5. If you allow thirty hours for the course then you can expect to spend about seven hours on lesson 5.
Set a starting date and a finishing date as targets. If you allow yourself thirty hours to do the whole course and if you commit three hours per week then the course will take ten weeks. Pick a date to start and stick to it! Only death and sickness should prevent your starting! Possibly a large win on the lottery might also delay the start.
Set a time each week for the lessons, the same time each week. Remember this is a discipline of time management. If you have set aside three hours per week and you have estimated how long you have to spend on each lesson then you have a very good idea of where you will be through the course at any given time. Now write down a timetable. Keep a diary on your progress and check it against your timetable.
Few people can remember complex things at the first go. Be prepared to go back over things. Most days I can barely remember what I had for breakfast but I do know where to go to check things. My own learning habits depend very much on reinforcement, that is, re-visiting lessons and doing practice exercises. A particularly good way to learn practical skills is to invent your own exercises.
And last of all: There are three golden rules for the exercises and questions:
If you can't remember the three rules, just do the exercises and questions.
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This publication is copyright David Beech and Learning Systems 1997-2002
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David Beech.
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