в 16:40, 26 мая 2010

2010-05-26T16:40:30Z

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2010-05-26T12:55:46Z

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==Comparison method based on delegate==

<source lang="vbnet">Module Module1
Class Employee
Public FirstNme As String
Public LastName As String
Public Title As String
Public Salary As Double
Public Sub New(ByVal LastName As String, ByVal FirstNme As String, _
ByVal Title As String, ByVal Salary As Double)
Me.FirstNme = FirstNme
Me.LastName = LastName
Me.Title = Title
Me.Salary = Salary
End Sub
End Class
Delegate Function Compare(ByVal A As Employee, ByVal B As Employee) As Boolean
Dim CompareMethod As New Compare(AddressOf CompareTitle)
Function CompareTitle(ByVal A As Employee, ByVal B As Employee) As Boolean
If (A.Title < B.Title) Then
CompareTitle = False
Else
CompareTitle = True
End If
End Function
Function CompareLastName(ByVal A As Employee, ByVal B As Employee) As Boolean
If (A.LastName < B.LastName) Then
CompareLastName = False
Else
CompareLastName = True
End If
End Function
Function CompareSalary(ByVal A As Employee, ByVal B As Employee) As Boolean
If (A.Salary < B.Salary) Then
CompareSalary = False
Else
CompareSalary = True
End If
End Function
Public Sub SortList(ByVal Employeelist() As Employee)
Dim I, J As Integer
Dim Temp As Employee
For I = 0 To Employeelist.Length - 2
For J = I + 1 To Employeelist.Length - 1
If (CompareMethod(Employeelist(I), Employeelist(J))) Then
Temp = Employeelist(I)
Employeelist(I) = Employeelist(J)
Employeelist(J) = Temp
End If
Next
Next
End Sub
Sub Main()
Dim EmployeeList(3) As Employee
EmployeeList(0) = New Employee("A","Z", "W", 49.99)
EmployeeList(1) = New Employee("Z","A", "J", 49.99)
EmployeeList(2) = New Employee("B", "X", "K", 49.99)
EmployeeList(3) = New Employee("P","O", "A", 39.99)
SortList(EmployeeList)
Console.WriteLine("By Title")
Dim EmployeeEntry As Employee
For Each EmployeeEntry In EmployeeList
Console.WriteLine(EmployeeEntry.LastName & " " & EmployeeEntry.Title & " " & EmployeeEntry.Salary)
Next
Console.WriteLine("By LastName")
CompareMethod = AddressOf CompareLastName
SortList(EmployeeList)
For Each EmployeeEntry In EmployeeList
Console.WriteLine(EmployeeEntry.LastName & " " & EmployeeEntry.Title & " " & EmployeeEntry.Salary)
Next
Console.WriteLine("By Salary")
CompareMethod = AddressOf CompareSalary
SortList(EmployeeList)
For Each EmployeeEntry In EmployeeList
Console.WriteLine(EmployeeEntry.LastName & " " & EmployeeEntry.Title & " " & EmployeeEntry.Salary)
Next
End Sub
End Module</source>
<pre class=codeResult>By Title
P A 39.99
Z J 49.99
B K 49.99
A W 49.99
By LastName
A W 49.99
B K 49.99
P A 39.99
Z J 49.99
By Salary
P A 39.99
Z J 49.99
B K 49.99
A W 49.99</pre>

==Define a delegate to be a pointer to a subroutine that has a string parameter.==

<source lang="vbnet">public class Test
public Shared Sub Main
Dim m_DisplayStringRoutine As StringDisplayerType
m_DisplayStringRoutine = AddressOf ShowStringInMessageBox " ShowStringInOutputWindow
m_DisplayStringRoutine("Hello world")
End Sub
Private Delegate Sub StringDisplayerType(ByVal str As String)
Private Shared Sub ShowStringInOutputWindow(ByVal str As String)
Console.WriteLine(str)
End Sub
Private Shared Sub ShowStringInMessageBox(ByVal str As String)
Console.WriteLine("+++"+str)

End Sub
End class</source>
<pre class=codeResult>+++Hello world</pre>

==Define delegate==

<source lang="vbnet">public class Test
Private Delegate Function NumEmployeesDelegate() As Integer
Private Delegate Function GetNameDelegate() As String
public Shared Sub Main
Dim emp As New Employee()
Dim show_name As GetNameDelegate
show_name = AddressOf emp.ToString
Console.WriteLine(show_name())

End Sub
End class

Public Class Employee
Public Shared Function GetNumEmployees() As Integer
Return 13
End Function
Public Overrides Function ToString() As String
Return "Employee"
End Function
End Class</source>
<pre class=codeResult>Employee</pre>

==Delegate Function==

<source lang="vbnet">Module Module1
Delegate Function Numbers(ByVal A As Double, ByVal B As Double) As Double
Function SubtractNumbers(ByVal A As Double, ByVal B As Double) As Double
SubtractNumbers = A - B
End Function
Function AddNumbers(ByVal A As Double, ByVal B As Double) As Double
AddNumbers = A + B
End Function
Sub Main()
Dim DoNumbers As New Numbers(AddressOf SubtractNumbers)
Console.WriteLine(DoNumbers.Invoke(100, 50))
DoNumbers = AddressOf AddNumbers
Console.WriteLine(DoNumbers.Invoke(100, 50))
End Sub
End Module</source>
<pre class=codeResult>50
150</pre>

==Math delegation==

<source lang="vbnet">Imports System
Module Test
Sub Main()
Console.WriteLine("Enter Operation to Perform")
PerformOp(New MathOperation(AddressOf Math.Sin))
PerformOp(New MathOperation(AddressOf Math.Cos))
PerformOp(New MathOperation(AddressOf Math.Tan))
End Sub
Delegate Function MathOperation(ByVal radians As Double) As Double
Private Sub PerformOp(ByVal op As MathOperation)
Dim angle As Double = 12
Dim radians As Double
radians = (angle / 360) * 2 * Math.PI
Dim result As Double
result = op.Invoke(radians)
result = Math.Round(result, 4)
Console.Writeline("Result = " & result.ToString())
End Sub
End Module</source>
<pre class=codeResult>Enter Operation to Perform
Result = 0.2079
Result = 0.9781
Result = 0.2126</pre>

==Multiple Delegates==

<source lang="vbnet">Module Module1
Delegate Sub NotifyInfo()
Dim ListOfDelegates(3) As NotifyInfo
Sub Testing()
Console.WriteLine("AAA")
End Sub
Sub Coding()
Console.WriteLine("BBB")
End Sub
Sub Meeting()
Console.WriteLine("CCC")
End Sub
Sub Main()
ListOfDelegates(0) = New NotifyInfo(AddressOf Coding)
ListOfDelegates(1) = New NotifyInfo(AddressOf Testing)
ListOfDelegates(2) = New NotifyInfo(AddressOf Meeting)
Dim NotifyAll As New NotifyInfo(AddressOf Coding)
NotifyAll = NotifyInfo.rubine(ListOfDelegates)
NotifyAll.Invoke()
End Sub
End Module</source>
<pre class=codeResult>BBB
AAA
CCC</pre>

==Use AddressOf to assign function to a delegate==

<source lang="vbnet">public class Test
Private Delegate Function NumEmployeesDelegate() As Integer
Private Delegate Function GetNameDelegate() As String
public Shared Sub Main
Dim emp As New Employee()
Dim show_num As NumEmployeesDelegate
show_num = AddressOf Employee.GetNumEmployees
Console.WriteLine(show_num().ToString)

End Sub
End class

Public Class Employee
Public Shared Function GetNumEmployees() As Integer
Return 13
End Function
Public Overrides Function ToString() As String
Return "Employee"
End Function
End Class</source>
<pre class=codeResult>13</pre>

==Use Delegate Sub==

<source lang="vbnet">Module Module1
Delegate Sub StringMethod(ByVal S As String)
Sub DisplayString(ByVal S As String)
Console.WriteLine(S)
End Sub
Sub UpperString(ByVal S As String)
Console.WriteLine(UCase(S))
End Sub
Sub Main()
Dim MyMethod As New StringMethod(AddressOf DisplayString)
MyMethod.Invoke("Visual Basic .Net Programming")
MyMethod = AddressOf UpperString
MyMethod.Invoke("Visual Basic .Net Programming")
End Sub
End Module</source>
<pre class=codeResult>Visual Basic .Net Programming
VISUAL BASIC .NET PROGRAMMING</pre>

==Uses delegates to sort random numbers (ascending or descending)==

<source lang="vbnet">Public Class Tester

Private Shared Function SortAscending(ByVal element1 As Integer, _
ByVal element2 As Integer) As Boolean
Return element1 > element2
End Function " SortAscending
Private Shared Function SortDescending(ByVal element1 As Integer, _
ByVal element2 As Integer) As Boolean
Return element1 < element2
End Function " SortDescending
Public Shared Sub Main
Dim mBubbleSort As New BubbleSort()
Dim mElementArray As Integer() = New Integer(9) {}
Dim randomNumber As Random = New Random()
Dim i As Integer
" create String with 10 random numbers
For i = 0 To mElementArray.GetUpperBound(0)
mElementArray(i) = randomNumber.Next(100)
Console.WriteLine(mElementArray(i))
Next

mBubbleSort.SortArray(mElementArray, AddressOf SortAscending)
For i = 0 To mElementArray.GetUpperBound(0)
Console.Write(mElementArray(i) & " " )
Next
Console.WriteLine()
mBubbleSort.SortArray(mElementArray, AddressOf SortDescending)
For i = 0 To mElementArray.GetUpperBound(0)
Console.Write(mElementArray(i) & " " )
Next
End Sub
End Class
Public Class BubbleSort
Public Delegate Function Comparator( _
ByVal element1 As Integer, _
ByVal element2 As Integer) As Boolean
Public Sub SortArray(ByVal array As Integer(), _
ByVal Compare As Comparator)
Dim i, pass As Integer
For pass = 0 To array.GetUpperBound(0)
For i = 0 To array.GetUpperBound(0) - 1
If Compare(array(i), array(i + 1)) Then
Swap(array(i), array(i + 1))
End If
Next " inner loop
Next " outer loop
End Sub " SortArray
Private Sub Swap(ByRef firstElement As Integer, _
ByRef secondElement As Integer)
Dim hold As Integer
hold = firstElement
firstElement = secondElement
secondElement = hold
End Sub " Swap
End Class</source>
<pre class=codeResult>77
24
72
44
64
75
23
44
93
73
23 24 44 44 64 72 73 75 77 93
93 77 75 73 72 64 44 44 24 23 "</pre>

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в 16:40, 26 мая 2010

Admin: 1 версия