Understanding Visual Basic: Integrated Development Environment and Object-Oriented Concepts

1. Visual Basic Starter Vocabulary

2. IDE • Integrated Development Environment • A setting in which programs are written, tested, debugged, etc. • You could write a C program in Notepad, compile and run by typing instructions at a command prompt • But “integrated” means the various aspects are all put together

3. VB is RAD • Visual Basic (VB) is considered a Rapid Applications Development (RAD) programming language since it makes the development of a Graphical User Interface (GUI) relatively simple • When you start to program in Visual Basic (VB), you are provided with a form

4. Form • Like a window • A container (surface) for “controls” • A form is an object; it has • Properties • Methods • Events • Actually the form you see is an object, but first a form is a class, then one “instantiates” an object of that class

5. Classes and Objects • A class is an abstract category of or template for objects • It collects the characteristics (properties) and actions (methods) common to the objects that belong to it • An object is a specific member of the class • When a specific object is made from the abstract class template, it is said to be an instantiation of the class • Initially the instantiations will be automatically done for us, but eventually we will have to do some of them for ourselves.

6. Example • Dog would be a class • It has properties, like breed, height, weight, etc. • It has methods, like barks, eats, runs, etc. • Lassie is an object • Lassie has specific properties • Her breed is Collie; her height is 36 inches; her weight is 90 pounds; etc. • The collection of specific properties is also referred to as the state of the object

7. Property • A property is like a variable; however, altering or accessing its value is usually done indirectly using a “guard” method. • The CommandButton object has • Height • Width • Position (left and top) • Caption • Etc.

8. Controls • Basic interface objects instantiated on a form. For example: • buttons • scroll bars • radio buttons • menus • Controls are not necessarily visible • E.g. timer

9. Event • A program detects that some action (an event) took place • The event may be initiated by • The user (e.g. a click) • The program (e.g. a timer) • The system (e.g. out of memory) • If the execution of a program (what is done, when it is done, etc.) depends on events, then the programming is said to be event-driven.

10. Method • Just as properties are variables tied to an object, methods are functions or procedures tied to an object • Methods are executed when an object receives a message (a “call” plus any arguments) • VB provides the shell of methods associated with certain events and objects (the click of a command button), but you can also make your own

11. Self-documentation • Documentation is the part of a program that has no effect on its execution but is meant to make the code more understandable to another programmer or yourself at a later date • Using variable names like “interest” so the variable name is directly associated with its purpose in the program

12. Hungarian Notation • It is a useful practice in VB to start the name of control objects with standard prefixes followed by a self-documenting name • For example, a Button that leads to printing when clicked might be called btnPrint • A good habit is to include some capital letters when naming variables • This is an example of Hungarian notation developed by Dr. Charles Simonyi