в 16:40, 26 мая 2010

2010-05-26T16:40:06Z

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2010-05-26T12:42:21Z

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==Array parameter passed by Value and by Reference==

<source lang="vbnet">
Imports System
public class MainClass
Shared Sub Main()
Dim A As Integer() = {1, 2, 3, 4, 5}
Dim B As Integer()
B = A
Console.WriteLine("Initial state ArrayTests")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("Array A:")
DisplayArray(A)
Console.WriteLine("Array B")
DisplayArray(B)
FunctionPassArrayByReference1(B)
Console.WriteLine("After FunctionPassArrayByReference1")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("Array A:")
DisplayArray(A)
Console.WriteLine("Array B")
DisplayArray(B)
A(0) = 1
B = A
FunctionPassArrayByReference2(B)
Console.WriteLine("After FunctionPassArrayByReference2")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("Array A:")
DisplayArray(A)
Console.WriteLine("Array B")
DisplayArray(B)
A(0) = 1
B = A
FunctionPassArrayByValue1(B)
Console.WriteLine("After FunctionPassArrayByValue1")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("Array A:")
DisplayArray(A)
Console.WriteLine("Array B")
DisplayArray(B)
A(0) = 1
B = A
FunctionPassArrayByValue2(B)
Console.WriteLine("After FunctionPassArrayByValue2")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("Array A:")
DisplayArray(A)
Console.WriteLine("Array B")
DisplayArray(B)

End Sub
Shared Public Sub FunctionPassArrayByReference1(ByRef Y As Integer())
Y(0) = 5
End Sub
Shared Public Sub FunctionPassArrayByReference2(ByRef Y As Integer())
Dim NewArray As Integer() = {2, 3, 4, 5, 6}
Y = NewArray
End Sub
Shared Public Sub FunctionPassArrayByValue1(ByVal Y As Integer())
Y(0) = 5
End Sub
Shared Public Sub FunctionPassArrayByValue2(ByVal Y As Integer())
Dim NewArray As Integer() = {2, 3, 4, 5, 6}
Y = NewArray
End Sub
Shared Public Sub DisplayArray(ByVal Y As Integer())
Dim X As Integer
For X = 0 To UBound(Y)
Console.Write(Y(X).ToString)
If X <> UBound(Y) Then
Console.Write(", ")
Else
Console.WriteLine()
End If
Next
End Sub
End Class

</source>

==Array passed By Value==

<source lang="vbnet">
Imports System
Public Class MainClass
Shared Sub Main(ByVal args As String())
Dim i As Integer
Dim firstArray As Integer()
Dim firstArrayCopy As Integer()
firstArray = New Integer() {1, 2, 3}
firstArrayCopy = firstArray
Console.WriteLine("Test passing array reference using ByVal.")
Console.WriteLine("Contents of firstArray before calling FirstDouble: ")
For i = 0 To firstArray.GetUpperBound(0)
Console.WriteLine(firstArray(i))
Next
" pass firstArray using ByVal
FirstDouble(firstArray)
Console.WriteLine("Contents of firstArray after calling FirstDouble: ")
" print contents of firstArray
For i = 0 To firstArray.GetUpperBound(0)
Console.WriteLine(firstArray(i) & " ")
Next
" test whether reference was changed by FirstDouble
If firstArray Is firstArrayCopy Then
Console.WriteLine("The references are equal.")
Else
Console.WriteLine("The references are not equal.")
End If

End Sub
" procedure modifies elements of array and assigns
" new reference (note ByVal)
Shared Sub FirstDouble(ByVal array As Integer())
Dim i As Integer
" double each element value
For i = 0 To array.GetUpperBound(0)
array(i) *= 2
Next
" create new reference, assign it to array
array = New Integer() {11, 12, 13}
End Sub
End Class

</source>

==Function with pass by value Parameter==

<source lang="vbnet">
Imports System
Public Class MainClass
Shared Sub Main()
Dim A() As String = {"HELLO", "GOODBYE"}
Console.WriteLine("Original first item in array is: " _
& A(0))
Console.WriteLine("Original second item in array is: " _
& A(1))
AFunction(A)
Console.WriteLine("After passing by value first item in array now is: " _
& A(0))
Console.WriteLine("After passing by value second item in array is: " _
& A(1))
End Sub
Shared Sub AFunction(ByVal Foo As String())
Foo(0) = "GOODBYE"
Foo(1) = "HELLO"
End Sub
End Class

</source>

==Modify Array Element By Value ==

<source lang="vbnet">
Imports System
Public Class MainClass
Shared Sub Main(ByVal args As String())
Dim array1 As Integer() = New Integer() {1, 2, 3, 4, 5}
Dim i As Integer
Console.WriteLine( "The values of the original array are:" & vbCrLf )
" display original elements of array1
For i = 0 To array1.GetUpperBound(0)
Console.WriteLine( " " & array1(i) )
Next
Console.WriteLine( vbCrLf & vbCrLf & _
"EFFECTS OF PASSING ARRAY ELEMENT " & _
"BY VALUE:" & vbCrLf & vbCrLf & "array1(3) " & _
"before ModifyElementByVal: " & array1(3) )
" array element passed by value
ModifyElementByVal(array1(3))

End Sub
Shared Sub ModifyElementByVal(ByVal element As Integer)
Console.WriteLine( vbCrLf & "Value received in " & _
"ModifyElementByVal: " & element )
element *= 2
Console.WriteLine( vbCrLf & "Value calculated in " & _
"ModifyElementByVal: " & element )
End Sub " ModifyElementByVal
End Class

</source>

==Object parameter passed by Value and by Reference==

<source lang="vbnet">
Imports System
public class MainClass
Shared Sub Main()
Dim A As New MyObject()
Dim B As MyObject = A
A.X = 1
Console.WriteLine("Initial state")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
FunctionPassObjectByReference1(B)
Console.WriteLine("After FobjByRef1")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
A.X = 1
B = A
FunctionPassObjectByReference2(B)
Console.WriteLine("After FobjByRef2")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
A.X = 1
B = A
FunctionPassObjectByValue1(B)
Console.WriteLine("After FobjByVal1")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
A.X = 1
B = A
FunctionPassObjectByValue2(B)
Console.WriteLine("After FobjByVal2")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())

End Sub
Shared Public Sub FunctionPassObjectByReference1(ByRef Y As MyObject)
Y.X = 5
End Sub
Shared Public Sub FunctionPassObjectByReference2(ByRef Y As MyObject)
Y = New MyObject()
Y.X = 5
End Sub
Shared Public Sub FunctionPassObjectByValue1(ByVal Y As MyObject)
Y.X = 5
End Sub
Shared Public Sub FunctionPassObjectByValue2(ByVal Y As MyObject)
Y = New MyObject()
Y.X = 5
End Sub
Class MyObject
Public X As Integer
End Class
End Class

</source>

==Passing arrays and individual array elements to procedures==

<source lang="vbnet">
Imports System
Public Class MainClass
Shared Sub Main(ByVal args As String())
Dim array1 As Integer() = New Integer() {1, 2, 3, 4, 5}
Dim i As Integer
Console.WriteLine( "The values of the original array are:" & vbCrLf )
" display original elements of array1
For i = 0 To array1.GetUpperBound(0)
Console.WriteLine( " " & array1(i) )
Next
ModifyArray(array1) " array is passed by reference
Console.WriteLine( vbCrLf & _
"The values of the modified array are:" & vbCrLf )
" display modified elements of array1
For i = 0 To array1.GetUpperBound(0)
Console.WriteLine(" " & array1(i) )
Next
End Sub
" procedure modifies array it receives (note ByVal)
Shared Sub ModifyArray(ByVal arrayParameter As Integer())
Dim j As Integer
For j = 0 To arrayParameter.GetUpperBound(0)
arrayParameter(j) *= 2
Next
End Sub " ModifyArray

End Class

</source>

==Squares three values ByVal and ByRef, displays results==

<source lang="vbnet">
Imports System
Public Class MainClass
Shared Sub Main(ByVal args As String())
Dim number1 As Integer = 2
Console.WriteLine("Passing a value-type argument by value:")
Console.WriteLine("Before calling SquareByValue, " & _
"number1 is {0}", number1)
SquareByValue(number1) " passes number1 by value
Console.WriteLine("After returning from SquareByValue, " & _
"number1 is {0}" & vbCrLf, number1)
Dim number2 As Integer = 2
Console.WriteLine("Passing a value-type argument" & _
" by reference:")
Console.WriteLine("Before calling SquareByReference, " & _
"number2 is {0}", number2)
SquareByReference(number2) " passes number2 by reference
Console.WriteLine("After returning from " & _
"SquareByReference, number2 is {0}" & vbCrLf, number2)
Dim number3 As Integer = 2
Console.WriteLine("Passing a value-type argument" & _
" by reference, but in parentheses:")
Console.WriteLine("Before calling SquareByReference " & _
"using parentheses, number3 is {0}", number3)
SquareByReference((number3)) " passes number3 by value
Console.WriteLine("After returning from " & _
"SquareByReference, number3 is {0}", number3)
End Sub

" squares number by value (note ByVal keyword)
Shared Sub SquareByValue(ByVal number As Integer)
Console.WriteLine("After entering SquareByValue, " & _
"number is {0}", number)
number *= number
Console.WriteLine("Before exiting SquareByValue, " & _
"number is {0}", number)
End Sub " SquareByValue
" squares number by reference (note ByRef keyword)
Shared Sub SquareByReference(ByRef number As Integer)
Console.WriteLine("After entering SquareByReference" & _
", number is {0}", number)
number *= number
Console.WriteLine("Before exiting SquareByReference" & _
", number is {0}", number)
End Sub " SquareByReference
End Class

</source>

==String parameter passed by Value and by Reference==

<source lang="vbnet">
Imports System
public class MainClass
Shared Sub Main()
Dim A As String = "Hello"
Dim B As String
B = A
Console.WriteLine(Chr(10) + "Initial state StringTests")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A: " + A + " B: " + B)
FunctionPassStringByReference1(B)
Console.WriteLine("After FunctionPassStringByReference1")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A: " + A + " B: " + B)
A = "Hello"
B = A
FunctionPassStringByReference2(B)
Console.WriteLine("After FunctionPassStringByReference2")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A: " + A + " B: " + B)
A = "Hello"
B = A
FunctionPassStringByReference3(B)
Console.WriteLine("After FunctionPassStringByReference3")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("Are A and B equal? " + (A = B).ToString())
Console.WriteLine("A: " + A + " B: " + B)
A = "Hello"
B = A
FunctionPassStringByValue1(B)
Console.WriteLine("After FunctionPassStringByValue1")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A: " + A + " B: " + B)
A = "Hello"
B = A
FunctionPassStringByValue2(B)
Console.WriteLine("After FunctionPassStringByValue2")
Console.WriteLine("Are A and B the same? " + (A Is B).ToString())
Console.WriteLine("A: " + A + " B: " + B)
End Sub
Shared Public Sub FunctionPassStringByReference1(ByRef Y As String)
Mid$(Y, 1, 1) = "A"
End Sub
Shared Public Sub FunctionPassStringByReference2(ByRef Y As String)
Y = "Hello"
End Sub
Shared Public Sub FunctionPassStringByReference3(ByRef Y As String)
Mid$(Y, 1, 1) = "H"
End Sub
Shared Public Sub FunctionPassStringByValue1(ByVal Y As String)
Mid$(Y, 1, 1) = "A"
End Sub
Shared Public Sub FunctionPassStringByValue2(ByVal Y As String)
Y = "Hello"
End Sub
End Class

</source>

==Structure parameter passed by Value and by Reference==

<source lang="vbnet">
Imports System
public class MainClass
Shared Sub Main()
Dim A As MyStruct
Dim B As MyStruct
A.X = 1
B = A
Console.WriteLine("Initial state StructTests")
Console.WriteLine("Are A and B the same? " + (A.Equals(B)).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
FunctionPassStructureByReference1(B)
Console.WriteLine("After FunctionPassStructureByReference1")
Console.WriteLine("Are A and B the same? " + (A.Equals(B)).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
A.X = 1
B = A
FunctionPassStructureByReference2(B)
Console.WriteLine("After FunctionPassStructureByReference2")
Console.WriteLine("Are A and B the same? " + (A.Equals(B)).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
A.X = 1
B = A
FunctionPassStructureByValue(B)
Console.WriteLine("After FunctionPassStructureByValue")
Console.WriteLine("Are A and B the same? " + (A.Equals(B)).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())
A.X = 1
B = A
FStructByVal2(B)
Console.WriteLine("After FStructByVal2")
Console.WriteLine("Are A and B the same? " + (A.Equals(B)).ToString())
Console.WriteLine("A.x: " + A.X.ToString() + " B.x " + B.X.ToString())

End Sub
Shared Public Sub FunctionPassStructureByReference1(ByRef Y As MyStruct)
Y.X = 5
End Sub
Shared Public Sub FunctionPassStructureByReference2(ByRef Y As MyStruct)
Y = New MyStruct()
Y.X = 5
End Sub
Shared Public Sub FunctionPassStructureByValue(ByVal Y As MyStruct)
Y.X = 5
End Sub
Shared Public Sub FStructByVal2(ByVal Y As MyStruct)
Y = New MyStruct()
Y.X = 5
End Sub

Structure MyStruct
Public X As Integer
End Structure
End Class

</source>

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в 16:40, 26 мая 2010

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