Visual Basic

Starter Vocabulary

IDE

Integrated Development EnvironmentA 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

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 simpleWhen you start to program in Visual Basic (VB), you are provided with a form

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

Classes and Objects

A class is an abstract category of or template for objectsIt collects the characteristics (properties) and actions (methods) common to the objects that belong to itAn 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 classInitially the instantiations will be automatically done for us, but eventually we will have to do some of them for ourselves.

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

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.

Controls

Basic interface objects instantiated on a form. For example: buttons scroll bars radio buttons menus

Controls are not necessarily visible E.g. timer

Event

A program detects that some action (an event) took placeThe 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.

Method

Just as properties are variables tied to an object, methods are functions or procedures tied to an objectMethods 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

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 dateUsing variable names like “interest” so the variable name is directly associated with its purpose in the program

Hungarian Notation

It is a useful practice in VB to start the name of control objects with standard prefixes followed by a self-documenting nameFor 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