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VB.Net Introduction. Visual Studio 2012 Demo. Start page: New project/ Open project/ Recent projects Starting project: File/New Project/ C# /VB/Other language Windows Windows form application Project name/Project folder Project windows: Form design view/Form code view

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visual studio 2012 demo
Visual Studio 2012 Demo
  • Start page: New project/ Open project/Recent projects
  • Starting project:
      • File/New Project/
        • C# /VB/Other language
        • Windows
          • Windows form application
        • Project name/Project folder
  • Project windows:
    • Form design view/Form code view
    • Solution Explorer
      • View/Solution Explorer
    • ToolBox
    • Property Window
      • Properties and Events
    • Server Explorer
    • Project/Add New Item
    • Property window example
introduction to visual basic net
Introduction to Visual Basic .Net
  • Event-driven programming
    • The interface for a VB program consists of one or more forms, containing one or more controls (screen objects).
    • Form and controls have events that can respond to. Typical events include clicking a mouse button, type a character on the keyboard, changing a value, etc.
    • Event procedure
slide4
Form
  • Properties:
    • Name, FormBorderStyle, Text, BackColor, BackImage, Opacity
  • Events:
    • Load, FormClosing, FormClosed
    • GotFocus, LostFocus
    • MouseHover, Click, DoubleCLick
common vb net controls
Common VB.Net Controls
  • TextBox
  • Label
  • Button
  • CheckBox
  • RadioButton
  • ListBox
  • ComboBox
  • PictureBox
text box
Text Box
  • Properties:
    • AutoSize, BorderStyle, CauseValidation, Enabled, Locked, Multiline, PasswordChar, ReadOnly, ScrollBar, TabIndex, Text, Visible, WordWrap, etc.
  • Properties can be set at the design time or at the run time using code.
  • To refer to a property:
    • ControlName.PropertyName
    • Ex. TextBox1.Text
    • Note: The Text property is a string data type and automatically inherits the properties and methods of the string data type.
typical vb net programming tasks
Typical VB.Net Programming Tasks
  • Creating the GUI elements that make up the application’s user interface.
    • Visualize the application.
    • Make a list of the controls needed.
  • Setting the properties of the GUI elements
  • Writing procedures that respond to events and perform other operations.
to add an event procedure
To Add an Event-Procedure
  • 1. Select the Properties window
  • 2. Click Events button
  • 3. Select the event and double-click it.
  • Note: Every control has a default event.
      • Form: Load event
      • Button control: Click event
      • Textbox: Text Changed event
    • To add the default event procedure, simply double-click the control.
slide9
Demo

FirstName

LastName

FullName

.Control properties

.Event: Click, MouseMove, FormLoad, etc.

.Event procedures

FullName: textBox3.Text textBox3.Text = textBox1.Text + " " + textBox2.Text

Demo: Text alignment (TextBox3.TextAlign=HorizontalAlign.Center)

TextBox3.BackColor=Color.Aqua

slide10
Demo

Num1

Num2

Sum =

.Control properties

.Event: Click, MouseMove, FormLoad, etc.

.Event procedures

Sum: textBox3.text=CStr(CDbl(textBox1.text)+CDbl(textBox2.text))

Or (CDbl(textBox1.text)+CDbl(textBox2.text)).toString

data conversion using vb functions or net methods
Data Conversion Using VB Functions or .Net Methods
  • VB functions: Cstr, Cdbl, …
  • .Net framework:
    • System.Convert
  • TextBox3.Text = (System.Convert.ToDouble(TextBox1.Text) + System.Convert.ToDouble(TextBox2.Text)).ToString
configure vb project
Configure VB Project
  • Project property page
    • Application:
      • Target framework
      • Startup form
    • Compile:
      • Target CPU
      • Option: explicit, strict, compare
    • References
  • Tools/Options
        • Environment
vb defaults
VB Defaults
  • Option Explicit:
    • On --- must declare variables before use
  • Option Strict:
    • Off --- VB will convert the data (implicit conversion)
  • Option Compare:
    • Binary --- case sensitive
    • Text --- case insensitive
  • Option Infer
    • On --- When you set Option Infer to On, you can declare variables without explicitly stating a data type. The compiler infers the data type of a variable from the type of its initialization expression.
variable declarations
Variable Declarations
  • Option Explicit
  • Dim variableName as DataType
  • Variable naming rules:
    • The first character must be a letter or an underscore character.
    • Use only letters, digits, and underscore.
    • Cannot contain spaces or periods.
    • No VB keywords
  • Naming conventions:
    • Descriptive
    • Consistent lower and upper case characters.
      • Ex. Camel casing: lowerUpper, employeeName
control naming conventions
Control Naming Conventions
  • The first three letters should be a lowercase prefix that indicates the control’s type.
    • frm, txt, lbl, btn.
  • The first letter after the prefix should be uppercase.
    • txtSalary, lblMessage
  • The part of the control name after the prefix should describe the control’s purpose in the application.
vb data types
VB Data Types
  • Boolean (True/False): 2 bytes
  • Byte: Holds a whole number from 0 to 255.
  • Char: single character
  • Date: date and time, 8 bytes.
  • Decimal: Real number up to 29 significant digits, 16 bytes
  • Double: real, 8 bytes
  • Single: real, 4 bytes
  • Integer: 4 bytes (int32, uint32)
  • Long: 8 bytes integer
  • Short: 2 bytes integer
  • String
  • Object: Holds a reference of an object
variable declaration examples
Variable Declaration Examples
  • Dim empName as String
  • Declare multiple variables with one Dim:
    • Dim empName, dependentName, empSSN as String
  • Dim X As Integer, Y As Single
  • Initiatialization
    • Dim interestRate as Double = 0.0715
variable default value
Variable Default Value
  • Variables with a numeric data type: 0
  • Boolean variables: False
  • Date variables: 12:00:00 AM, January 1 of the year 1.
  • String variables: Nothing
arithmetic and string operators
Arithmetic and String Operators
  • Arithmetic operators:

+, -, *, /. ^

\ operator: Divides two numbers and returns an integer result.

Mod: Divides two numbers and returns only the remainder.

      • Example: 10 mod 3

.Net Math class:

Math.Pow(2, 3)

  • String Concatenation: &, +
  • Compound operator:

:X= X+1 or X +=1

example
Example

Dim dividend, divisor, quotient, remainder As Integer

dividend = CInt(TextBox1.Text)

divisor = CInt(TextBox2.Text)

quotient = dividend \ divisor

remainder = dividend Mod divisor

TextBox3.Text = quotient

TextBox4.Text = remainder

tostring
ToString
  • MessageBox.Show("quotient is:" + quotient)
    • Trigger error
  • MessageBox.Show("quotient is:" + quotient.ToString)
  • MessageBox.Show("Remainder is: " + remainder.ToString)
  • Option Strict
change machine to return smallest number of coins
Change Machine to Return Smallest Number of Coins

Dim changes, quarters, dimes, nickles, pennies As Integer

changes = CInt(TextBox1.Text)

quarters = changes \ 25

dimes = (changes - quarters * 25) \ 10

nickles = (changes - quarters * 25 - dimes * 10) \ 5

pennies = changes - quarters * 25 - dimes * 10 - nickles * 5

TextBox2.Text = quarters

TextBox3.Text = dimes

TextBox4.Text = nickles

TextBox5.Text = pennies

fv pv 1 rate year
FV = PV * (1 +Rate) Year

Dim PV, Rate, Term, FV As Double

PV = CDbl(TextBox1.Text)

Rate = CDbl(TextBox2.Text)

Term = CDbl(TextBox3.Text)

FV = PV * (1 + Rate) ^ Term

TextBox4.Text = FV.ToString("C")

formatting numbers with the tostring method
Formatting Numbers with the ToString Method
  • The ToString method can optionally format a number to appear in a specific way
  • The following table lists the “format strings” and how they work with sample outputs
data conversion
Data Conversion
  • Implicit conversion: When you assign a value of one data type to a variable of another data type, VB attempts to convert the value being assigned to the data type of the variable if the OptionStrict is set to Off.
  • Explicit conversion:
    • VB.Net Functions: CStr, Ccur, CDbl, Cint, CLng, CSng, Cdate,Val, etc.
    • .Net System.Convert
  • Type class’s methods:
    • toString
date data type
Date Data Type
  • Variables of the Date data type can hold both a date and a time. The smallest value is midnight (00:00:00) of Jan 1 of the year 1. The largest value is 11:59:59 PM of Dec. 31 of the year 9999.
  • Date literals: A date literal may contain the date, the time, or both, and must be enclosed in # symbols:
    • #1/29/2013#, #1/31/2013 2:10:00 PM#
    • #6:30 PM#, #18:30:00#
date examples
Date Examples
  • Date Literal Example:
    • Dim startDate as dateTime
    • startDate = #1/29/2013#
  • Use the System.Convert.ToDateTime function to convert a string to a date value:
    • startDate = System.Convert.ToDateTime(“1/30/2003”)
    • If date string is entered in a text box:
      • startDate = System.Convert.ToDateTime(txtDate.text)
      • Or startDate=Cdate(txtDate.text)
  • Date data type format methods:
    • .ToLongDateString, etc.
some date functions
Some Date Functions
  • Now(): Current date and time
  • Today(): Current date
  • TimeOfDay
  • DateDiff:
  • Demo
    • Days between two dates
    • Days to Christmas
      • DateDiff(DateInterval.Day, Today(), #7/4/2013#)
    • Date data type properties and methods
using online help
Using Online Help
  • MSDN VB Developer Center
    • http://msdn.microsoft.com/en-us/vstudio/hh388573.aspx
    • Learn/Visual Basic language
the if then statement
The If … Then Statement
  • If condition Then

Statements

  • End If
  • If condition Then

Statements

Else

Statements

  • End If
  • Condition:
    • Simple condition:
      • Comparison of two expressions formed with relational operators:>, <, =, < >, >=, <=
      • Boolean variable
    • Complex condition:
      • Formed with logical operators: ( ), Not, And, Or
example1
Example
  • State University calculates students tuition based on the following rules:
    • State residents:
      • Total units taken <=12, tuition = 1200
      • Total units taken > 12, tuition = 1200 + 200 per additional unit.
    • Non residents:
      • Total units taken <= 9, tuition = 3000
      • Total units taken > 9, tuition = 3000 + 500 per additional unit.
decision tree
Decision Tree

Units <= 12 or Not

Resident or Not

Units <= 9 or Not

elseif statement
ELSEIF Statement
  • IF condition THEN

statements

[ELSEIF condition-n THEN

[elseifstatements]

[ELSE

[elsestatements]]]

End If

select case structure
Select Case Structure
  • SELECT CASE testexpression

[CASE expressionlist-n

[Statements]

[CASE ELSE

[elsestatements]

END SELECT

select case example
Select Case Example
  • SELECT CASE temperature

CASE <40

TextBox1.text=“cold”

CASE < 60

TextBox1.text=“cool”

CASE 60 to 80

TextBox1.text=“warm”

CASE ELSE

TextBox1.text=“Hot”

End Select

slide36
The Expression list can contain multiple expressions, separated by commas.

Select Case number

Case 1, 3, 5, 7, 9

textBox1.text=“Odd number”

Case 2, 4, 6, 8, 10

textBox1.text=“Even number”

Case Else

End Select

slide37
Loop
  • FOR index = start TO end [STEP step]

[statements]

[EXIT FOR]

NEXT index

DO [{WHILE| UNTIL} condition]

[statements]

[EXIT DO]

LOOP

slide38

Find the Sum of All Even Numbers between 1 and N

Dim sumEven, myN, i As Integer

myN = CInt(TextBox1.Text)

sumEven = 0

For i = 1 To myN

If i Mod 2 = 0 Then

sumEven += i

End If

Next

MessageBox.Show("The sum of even numbers is: " + sumEven.ToString)

do while
Do While

sumEven = 0

i = 1

Do While i <= myN

If i Mod 2 = 0 Then

sumEven += i

End If

i += 1

Loop

MessageBox.Show("The sum of even numbers is: " + sumEven.ToString)

with end with
With … End With

Convenient shorthand to execute a series of statements on a single object. Within the block, the reference to the object is implicit and need not be written.

With TextBox1

.Height = 250

.Width = 600

.Text = “Hello”

End With

function
Function

Private Function tax(salary) As Double

tax = salary * 0.1

End Function

  • Or

Private Function tax(salary) As Double

Return salary * 0.1

End Function

procedures
Procedures

. Sub procedure:

Sub SubName(Arguments)

End Sub

  • To call a sub procedure SUB1

CALL SUB1(Argument1, Argument2, …)

    • Or

SUB1(Argument1, Argument2, …)

call by reference call by value
Call by Reference Call by Value
  • ByRef
    • The address of the item is passed. Any changes made to the passing variable are made to the variable itself.
  • ByVal
    • Default
    • Only the variable’s value is passed.
byref example
ByRef Example

Private Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load

Dim myX, myY As Integer

myX = 10

test(myX, myY)

MessageBox.Show(myY)

End Sub

Private Sub test(x As Integer, ByRef y As Integer)

y = 2 * x

End Sub

byref byval example
ByRef, ByVal example

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim myStr As String

myStr = TextBox1.Text

Call ChangeTextRef (myStr)

TextBox1.Text = myStr

End Sub

Private Sub ChangeTextRef(ByRef strInput As String)

strInput = "New Text"

End Sub

variable scope
Variable Scope
  • Block-level scope: declared within a block of code terminated by an end, loop or next statement.
    • If city = “Rome” then
      • Dim message as string = “the city is in Italy”
      • MessageBox.Show(message)
    • End if
  • Procedural-level scope: declared in a procedure
  • Class-level, module-level scope: declared in a class or module but outside any procedure with either Dim or Private keyword.
  • Project-level scope: a module variable declared with the Public keyword.
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