Library tutorials & articles

Introduction to Class Programming

By Dante Salvador, published on 05 Sep 2003
Page 1 of 12
  1. Introduction
  2. What is a Class
  3. Why Use Class?
  4. Fundamental Concepts About Class
  5. Building Your First Class
  6. Properties Of a Class
  7. Property Get/Let
  8. Read-Only Property
  9. Write-only property
  10. Method of a Class
  11. Choosing Between Methods or Properties
  12. Summary

Introduction

In application program development, one of the most important considerations is the program's ability to accurately represent our perception of the real world. This requires the program to incorporate a realistic data model. Such a program is certainly easier to understand than one that performs its task without using a data model.

In order to develop a data model, we begin with the contention that the real world consists of entities and relationship.

An entity is defined as a live being, object or abstraction that can be described in terms of certain characteristic, and is similar to, but distinct from, entities of the same type.

An entity set is a collection of entities of the same type. For example, the books in your personal library make up an entity set; this book that you are reading now is a member of the entity set. You are a student, and therefore, you are member of the entity students of your college.

Each member of an entity set is different from the other member of the same set. The difference stem from their individual characteristic, called attributes. For example, a book is different from all other book because of its subject matter, author, publisher, design characteristic and unique ISBN book number. As a member of entity set of students, you are different from the rest of the student in your college because of your characteristic, such as your social security number, name, and so on.

In addition to entity set, the real world teems with all kinds of relationship. A relationship is an association among member of one or more entity set. A relationship set is a set of similar but distinct relationships of the same type. For example, class enrollment can be regarded as a relationship set between the entities sets of students and courses. The fact that you own a book can be seen as a relationship between you, a member of the entity set of students, and your book, a member of the entity set of textbooks.

One way you can represent entity set in Visual Basic is by using Classes and Objects. Fore example, the structure of Students below can be use to represent the student entity set or any its member in terms of their attributes, such as Student_ID, FirstName, LastName,  MajorCode, YearLevel and BirthDate.

In Visual Basic, you can represents relationship set by providing the former entity object with an object property to the latter. For example a typical Enrollment entity might expose a Student entity. The relationship set enrollment can be modeled using this structure:Student_ID, CourseNumber, AcademicYear, Semester and FinalLetterGrade

Comments

  1. Vincent Bloemen
    26 Jun 2009 at 13:14

    Wouw, thanks for this great explanation on how to use and make classes. I always coded in VB with function in normal Modules, now i'm going one step further... Trying it out...

  2. jakaria pervez
    23 Jun 2009 at 10:37

    Great Tutorial !! Helped me a lot

  3. The Nguyen
    07 Mar 2009 at 10:54
    This is great tutorial! Thank you sooooo much.
  4. Edi Winarko
    07 Jun 2008 at 11:55

    [quote user="Developer Fusion Bot"]

    This thread is for discussions of Introduction to Class Programming.

    [/quote]

    This was the best explanation to "class", I have ever come across. Hats off to you.

  5. Bhavani Josyula
    12 Jul 2007 at 12:36

    Hello Sir,

    I have just seen u'r examples for class module.u'r explaination is simply superb!!!!

    now i clearly understood the class module concept in VB.

     

    Thanks

    Bhavani Josyula

  6. Craig Nelson
    15 May 2007 at 16:10
    This was a very good fundamental article on the use of classes in VB. looking forward to additional more advance content
  7. davulcu
    16 May 2006 at 11:35

    It s a great sample about the class programming. However, it s still uncertain for me where I can use this in real life.

    Can anyone give me an example ?

  8. kirov
    05 Oct 2005 at 19:12

    what kind of help you wants from me. i mean to clear out your visual basic basics by giving you some tutorials or anything else. bye

  9. wan_rids2020
    29 Sep 2005 at 12:25
    hello sir, can you teach me the visual basic programing and where to start because i don't have a basic in this software. before this, i was try to learn this programe from e_book but it's looking so hurt to learn without a teacher.
    I would appericiate if u can show me the way to learn this programe.
    TQ
  10. T. Lowell Dent
    16 Jul 2005 at 02:59
    Thanks, Dante Salvador, for your excellent and lucid tutorial on Class Programming.
    I have worn Google to a frazzle looking for help. most of which was comprised of a few samples.
    You have helped "elucidate" me with both the why and how-to and that is no small task.
    Thanks so much for your efforts and help.
  11. kirov
    09 Jun 2005 at 17:34

    What a tutorial !! man i like it. this tutorial shows me another side of visual basic wow!!

  12. satinder_jit
    23 Dec 2004 at 13:40

    This is really a good tutorial on Visual Basic. I was really coinfused between let, get properties. But this is the final place which solved ll my problems

  13. Sparvhok
    22 Oct 2003 at 11:52

    vbexplorer.com has also an excellent oop tutorial, if youre looking for some more,
    and I have found a german article at vbarchiv.de that seems very good (i can
    tell because I studied german when in grad. school, swe).


    Maybe I should try an translate it to english...

  14. Joe Campbell
    20 Sep 2003 at 06:32

  15. leisha
    10 Sep 2003 at 17:41
    At one time I studied programming in Pascal & Fortran --- have forgotten lots of basics....I have read thru many VB tutorials etc but never have I so clearly had the 'light bulb' go on.  Thank-you for a well organized presentation.  Look forward to your future articles.
  16. Developer Fusion Bot
    01 Jan 1999 at 00:00

    This thread is for discussions of Introduction to Class Programming.

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