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CVEV 118/698 Visual Basic

Learn about Visual Basic programming language, IDE, controls, components, event-driven programming, variable declaration, coding steps, and more.

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CVEV 118/698 Visual Basic

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  1. CVEV 118/698 Visual Basic Lecture 1 Prof. Mounir Mabsout Expert 1: Elsa Sulukdjian Expert 2: Walid El Asmar

  2. Introduction • Visual Studio 6.0: Collection of Microsoft Visual development applications (Visual C++, Visual J++, Visual Basic, etc…) • VB is a programming language. 6 Versions launched since its creation in the 90’s. • “Easy and powerful tool for developing Windows applications in Basic.” Bill Gates.

  3. VB Development Environment • Integrated Development Environment (IDE): visual environment to develop, run, test and debug. • Controls: generally visual, and readymade components, assigned a set of properties (I.e. Text Box, Button, List Box, etc…). • IntelliSense: Microsoft’s sophisticated completion technology. It simplifies the coding process. • Event driven programming: flow of the application dictated by the user actions (click of a mouse, keystrokes, etc…).

  4. VB IDE menu bar Toolbar Project Explorer Toolbox Properties window Immediate window Form layout

  5. VB IDE Components • Menu Bar: contains all commands needed to run VB (File, Edit, View etc…). • Toolbars: quick access to commonly used menu commands. • Project Explorer: displays the project’s components. • Toolbox: contains icons of the controls that can be placed on the project’s Forms to create the application’s interface. • Properties Window: Shows the property settings of the selected control (size, caption, color, etc…).

  6. VB IDE Components (Cont’d) • Form Designer: Main window in which one can design and edit the application’s user interface. In this window the user can enter and edit the application’s code. It displays two windows: Form and Code window. • Form Layout: Shows the initial positions of the forms in the application. It is useful in multiple forms applications. • Immediate Window: Debugging tool.

  7. Programming Steps • Step 1: Customize the windows that the user sees. I.e. placing controls and components on the layouts of the project’s Forms. • Step 2: Decide on the events each control should recognize. • Step 3: Coding the event procedures for those events.

  8. Variable Declaration • Visual Basic code works in two modes: • Implicit: does not require variable declaration • Explicit: requires variable declaration • Declare variables using Dim VariableNameAs DataType Example: Dim length As Integer Dim greetings As String

  9. Variable Types • Numeric: stores numbers • String: stores text • Variant: stores any type of data • Boolean: true/false • Date • Object

  10. Implicit Example Public Sub VBImplicit() x = 5 y = “Hello” End Sub Explicit Example Start code window by: Option Explicit […] Public Sub VBExplicit() Dim x As Integer, y As String x = 5 y = “Hello” End Sub Implicit/Explicit • Implicit: default VB mode, x and y stored as variants • Explicit: x can only store integers, y only strings • ALWAYS use explicit mode, it reduces errors

  11. Variable Scope Code Form 1 Form1 Variables Sub1 Sub1 Variables ... Sub2 Sub2 Variables Code Form 2

  12. Variable Scope (cont’d) • The same variable x is needed in both subroutines and therefore is defined as a global variable (I.e. declaration outside subs) • There is a different local variable y for each subroutine (I.e. declaration inside subs) Dim x As Integer Public Sub FirstSub() x = 5 Dim y As Integer End Sub Public Sub SecondSub() x = 6 Dim y As String End Sub

  13. Variable Generalities • Variable names need to be significant for clear coding practice. • Don’t be shy of using long names. • Usually the first character(s) indicate the variable type (e.g): • Integer: int… Dim intLength As Integer • String: str… • Double: dbl… • Text Control: txt • Etc.

  14. Constants • Constants do not change their value during the execution of the program. • Declaration: Const ConstantName As DataType Public Const pi As Double = 3.14159265358979

  15. Arrays • Arrays hold a set of related data. • Declaration: Dim ArrayName(ArraySize) As DataType Dim strNames(15) As String orDim strNames(1 To 16) As String strNames is an array that holds 16 string values. • Multidimensional arrays: Dim dblTemperature(99,99) As Double

  16. Dynamic Arrays • Size not defined at the beginning of the program: Dim dblMatrix() as Double • You can re-dimension the array once you know the size of the array: ReDim dblMatrix(UserCount,UserCount)

  17. What’s Next • Basic VB syntax • Functions and Subroutines • Common VB controls

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