Visual Basic.NET How to Program (PDF)

266 Arrays Chapter 7
48 ' declare array references
49 Dim secondArray As Integer()
50 Dim secondArrayCopy As Integer()
51
52 ' allocate secondArray and copy its reference
53 secondArray = New Integer() {1, 2, 3}
54 secondArrayCopy = secondArray
55
56 Console.WriteLine(vbCrLf & "Test passing array " & _
57 "reference using ByRef.")
58 Console.Write("Contents of secondArray before " & _
59 "calling SecondDouble: ")
60
61 ' print contents of secondArray before procedure call
62 For i = 0 To secondArray.GetUpperBound(0)
63 Console.Write(secondArray(i) & " ")
64 Next
65
66 ' pass secondArray using ByRef
67 SecondDouble(secondArray)
68
69 Console.Write(vbCrLf & "Contents of secondArray " & _
70 "after calling SecondDouble: ")
71
72 ' print contents of secondArray after procedure call
73 For i = 0 To secondArray.GetUpperBound(0)
74 Console.Write(secondArray(i) & " ")
75 Next
76
77 ' test whether the reference was changed by SecondDouble
78 If secondArray Is secondArrayCopy Then
79 Console.WriteLine(vbCrLf & "The references are " & _
80 "equal.")
81 Else
82 Console.WriteLine(vbCrLf & "The references are " & _
83 "not equal.")
84 End If
85
86 End Sub ' Main
87
88 ' procedure modifies elements of array and assigns
89 ' new reference (note ByVal)
90 Sub FirstDouble(ByVal array As Integer())
91 Dim i As Integer
92
93 ' double each element value
94 For i = 0 To array.GetUpperBound(0)
95 array(i) *= 2
96 Next
97
98 ' create new reference and assign it to array
99 array = New Integer() {11, 12, 13}
100 End Sub ' FirstDouble
Fig. Fig. 7.9 7.9 Passing an array reference with ByVal and ByRef (part 2 of 3).