Visual Basic.NET How to Program (PDF)

Chapter 4 Control Structures: Part 1 137
With visual programming, the IDE actually generates program code that creates the GUI. This
code contains instructions for creating the form and every control on it.
Windows application code is contained in a class. Like modules, classes are logical groupings of
procedures and data that simplify program organization.
Using keyword Inherits to extend from class Form enables programmers to create forms
quickly, without “reinventing the wheel.” Every Windows application consists of at least one class
that Inherits from class Form in the System.Windows.Forms namespace.
The region of collapsed code labelled Windows Form Designer generated code contains
the code created by the IDE for the form and its controls, as well as code that enables the program
to run.
Forms and controls contain a set of default properties, which are displayed initially in the Properties
window when a form or control is selected. These default properties provide the initial
characteristics a form or control has when it is created.
When a change is made in design mode, such as changing a property value, the Windows Form
Designer creates code that implements the change.
Often it is necessary to modify a property while a program is running. In Windows applications,
such code is placed in a procedure that executes when the form is loaded, which can be created by
double-clicking the form in design view.
In Visual Basic, properties are access ed by placing the property name (e.g., Text) after the class
name (e.g., lblWelcome), separated by the dot operator.
TERMINOLOGY
&= (string concatenation assignment operator) declaration
*= (multiplication assignment operator) default property
+= (addition assignment operator) definite repetition
/= (division assignment operator) diamond symbol
= (assignment operator) division by zero
-= (subtraction assignment operator) Do While/Loop repetition structure
\= (Integer division assignment operator) Do Until/Loop repetition structure
^= (exponentiation assignment operator) Double primitive data type
action symbol double-selection structure
action/decision model of programming Else keyword
algorithm ElseIf keyword
attribute end of data entry
behavior entry point of control structure
body of a While exit point of control structure
building block expanded code
collapsed code first refinement
complete representation of a program flag value
conditional expression floating-point division
connector symbol floating-point number
constant flow of control
control structure flowchart
control-structure nesting flowline
control-structure stacking fractional result
counter GoTo elimination
counter-controlled repetition “GoTo-less programming”
decision symbol graphical representation of an algorithm