cp2028 visual basic programming 2
DESCRIPTION
CP2028 Visual Basic Programming 2. Week 1 Lecture 1 & 2 Introduction to the module The VB module set Contents and structure of this module Review of the Visual Basic environment Review of programming practices Variables & Scope. CP2028 Module Aims and Objectives. - PowerPoint PPT PresentationTRANSCRIPT
Week 1 Lecture 1 Slide 1CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
CP2028Visual Basic Programming 2
Week 1 Lecture 1 & 2– Introduction to the module
The VB module set Contents and structure of this module
– Review of the Visual Basic environment– Review of programming practices
– Variables & Scope
Week 1 Lecture 1 Slide 2CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
CP2028 Module Aims and Objectives
Reinforce the skills and knowledge gained in VB1.
Further develop programming abilities. Topics covered include:
– storing and accessing information in files– using Databases within VB.– File handling– error handling
Week 1 Lecture 1 Slide 3CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
The Visual Basic module set.
CP1007VB1
CP2028VB2
CP3013App Dev in VB
CP2030VB For C++
CP1000S.P. in C++
Week 1 Lecture 1 Slide 4CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Introduction to the Module [1]The Module Guide
The module consists of 12 weeks of study, plus a revision week.
As in VB1 the aim is to increase your skills and knowledge in program design and development.
Visual Basic is the target language, but the skills gained are applicable to other languages.
Week 1 Lecture 1 Slide 5CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Introduction to the Module [2]
Timetable details (see module guide)– 2 x 1-hour lectures per week– Tutorial– Workshop
Weekly contents
Assessments– Coursework– Exam
Week 1 Lecture 1 Slide 6CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Review of V.B. Environment
Identify the components of the VB design environment?
?
?
?
?
?
Week 1 Lecture 1 Slide 7CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Review of V.B. Environment
Identify the components of the VB design environment?
Code
MenuBar
?
Week 1 Lecture 1 Slide 8CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Review of V.B. Environment
Identify the components of the VB design environment?
?
?
?
?
?
Week 1 Lecture 1 Slide 9CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Review of V.B. Environment
Identify the components of the VB design environment?
Form
MenuBar
Control Toolbox
Project Window
PropertiesWindow
Week 1 Lecture 1 Slide 10CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Visual Basic Program Structure.
Project File– ‘.VBP’
Form Files– ‘.FRM’– ‘.FRX’
Modules– ‘.BAS’
Custom Controls– ‘.VBX’ files
Week 1 Lecture 1 Slide 11CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Control Bar - How many controls can you identify?
StandardEdition
ProfessionalEdition
Week 1 Lecture 1 Slide 12CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Control bar - Properties
Name
Run Time Vs Design Time (Startup Defaults)
Setting control positions when placeon form Vs via the properties window
What if we want to resize our formsdo we resize controls? How? Are there tools to do it?
Week 1 Lecture 1 Slide 13CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Review of Event Driven Programming
Application program is composed of a number of subroutines, which are triggered by events within the environment.
– Typical events include Mouse-click Keyboard use Field value changes
Events happen to a control.– Mostly user generated events– Controls can also cause events
Week 1 Lecture 1 Slide 14CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Visual Basic Event Processing
Trigger Event
Code Executed
Week 1 Lecture 1 Slide 15CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Types of Events
Events can be classified as:
User generated– (e.g. command button click)
Computer generated– (e.g. specific time elapsed, from a timer control)
Program generated– (i.e. program explicitly generates an event from within the code)
Week 1 Lecture 1 Slide 16CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Visual Basic Events
The events that can happen to a control are pre-determined
Each type of control has a relevant set of events
The events that can happen to a Command Button
Week 1 Lecture 1 Slide 17CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Programming Practices
We need to consider
– Control naming conventions
– Variable naming conventions
– Code documentation
Week 1 Lecture 1 Slide 18CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Scope of Variables
Shows declarationsat form level, knownas: General Declarations
Shows variabledeclarations withinan event handler
Form1General Declarations
Sub Command1_Click ()
Sub Command2_Click ()
Dim sName1 As StringDim iNum1 As Integer
Dim sName2 As StringDim iNum2 As Integer
Dim sName3 As StringDim iNum3 As Integer
Available variables:sName1, sName2, iNum1, iNum2
Available variables:sName1, sName3, iNum1, iNum3
Week 1 Lecture 1 Slide 19CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Scope The general rule is to declare variables at
the lowest possible level.
Ie Control level
Form level Module level
Week 1 Lecture 1 Slide 20CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Question Calculator
Create a front end for a simple calculator, You should be able to accept two numbers and perform addition, subtraction, multiplication and division.
Week 1 Lecture 1 Slide 21CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Question calculator
Try the calculator with 5 divide 0 !!!
Why is the application not working ?
How can we correct the problem ?
Week 1 Lecture 1 Slide 22CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Solution
Week 1 Lecture 1 Slide 23CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Code
Week 1 Lecture 1 Slide 24CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
code
Week 1 Lecture 1 Slide 25CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Static Variables A static variable will hold its value when it goes
out of scope:Sub Command1_Click()
'declare variablesDim iDimCount As IntegerStatic iStaticCount As Integer
'increment variables iDimCount = iDimCount + 1 iStaticCount = iStaticCount + 1
'display variables Label3.Caption = Str$(iDimCount) Label4.Caption = Str$(iStaticCount)End Sub
A static variable can only be declared inside a procedure
Note the use of a comment Note use of Str$ function
Week 1 Lecture 1 Slide 26CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
Static Variables: Effects
The effect of using a static variable can be seen below:
This is has the same effect as if the variable had been declared at the form’s general declaration level
Except the scope is local to the procedure
Week 1 Lecture 1 Slide 27CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
CP2028Visual Basic programming 2
Week 1 - Summary– Structure of this module and its position in the
VB module set.– Review of VB environment.– Review of event-driven programming
Week 1 Lecture 1 Slide 28CP2028 Visual Basic Programming 2 “The VB Team” Copyright © University of Wolverhampton
End of Lecture
Click House to Return to Main Menu