' Visual Basic 2008 9.0 .NET Examples - Methods and Arguments - Procedures and Functions : 
Module Example1
    Sub Main()
        Dim value1 As Integer = 5
        ShowDouble(value1)                                                 ' (1)
        '
        Dim value2 As String = "test"
        ShowDouble(value2)                                                 ' (2)
        '
        Console.ReadLine()
    End Sub
    Sub ShowDouble(ByVal value As Integer)                                 ' (1)
        Console.WriteLine(value * 2)
    End Sub
    Sub ShowDouble(ByVal word As String)                                   ' (2)
        Console.WriteLine(word & word)
    End Sub
End Module
Module Example2
    Sub Main()
        Console.WriteLine(GetSum(1, 2))
        Console.WriteLine(GetSum(1, 2, 3))
        Console.WriteLine(GetSum(1, 2, 3, 4))
        '
        Console.ReadLine()
    End Sub
    Function GetSum(ByVal value1 As Integer, _
                    ByVal value2 As Integer) As Integer
        GetSum = value1 + value2
    End Function
    Function GetSum(ByVal value1 As Integer, _
                    ByVal value2 As Integer, _
                    ByVal value3 As Integer) As Integer
        GetSum = value1 + value2 + value3
    End Function
    Function GetSum(ByVal value1 As Integer, _
                    ByVal value2 As Integer, _
                    ByVal value3 As Integer, _
                    ByVal value4 As Integer) As Integer
        GetSum = value1 + value2 + value3 + value4
    End Function
End Module
Module Exercise1Task
    Sub Main()
        'Console.WriteLine(GetCombination("abc", "def"))
        'Console.WriteLine(GetCombination(1, 2))
        'Console.WriteLine(GetCombination(True, True))
        'Console.WriteLine(GetCombination(True, False))
        'Console.WriteLine(GetCombination(False, True))
        'Console.WriteLine(GetCombination(False, False))
        '
        Console.ReadLine()
    End Sub
End Module
Module Exercise1Solution
    Sub Main()
        Console.WriteLine(GetCombination("abc", "def"))
        Console.WriteLine(GetCombination(1, 2))
        Console.WriteLine(GetCombination(True, True))
        Console.WriteLine(GetCombination(True, False))
        Console.WriteLine(GetCombination(False, True))
        Console.WriteLine(GetCombination(False, False))
        '
        Console.ReadLine()
    End Sub
    Function GetCombination(ByVal value1 As String, _
                            ByVal value2 As String) As String
        GetCombination = value1 & value2
    End Function
    Function GetCombination(ByVal value1 As Integer, _
                            ByVal value2 As Integer) As Integer
        GetCombination = value1 + value2
    End Function
    Function GetCombination(ByVal value1 As Boolean, _
                            ByVal value2 As Boolean) As Boolean
        GetCombination = value1 AndAlso value2
    End Function
End Module
Module Example3
    Sub Main()
        Console.WriteLine(GetPower(3, 3))
        Console.WriteLine(GetPower(3))                                     ' (1)
        '
        Console.ReadLine()
    End Sub
    Function GetPower(ByVal base As Integer, _
                      Optional ByVal exponent As Integer = 2) As Integer
        GetPower = base ^ exponent
    End Function
End Module
Module Example4
    Sub Main()
        ShowSum(1)       ' value1 = 1 | value2 = 2 | value3 = 3            ' (1)
        ShowSum(2, 3)    ' value1 = 2 | value2 = 3 | value3 = 3            ' (1)
        ShowSum(4, , 5)  ' value1 = 4 | value2 = 2 | value3 = 5            ' (1)
        ShowSum(6, 7, 8) ' value1 = 6 | value2 = 7 | value3 = 8            ' (1)
        '
        ShowSum(value1:=1)                                                 ' (2)
        ShowSum(value1:=2, value2:=3)                                      ' (2)
        ShowSum(value1:=4, value3:=5)                                      ' (2)
        ShowSum(value1:=6, value2:=7, value3:=8)                           ' (2)
        '
        ShowSum(value3:=5, value1:=4)                                      ' (3)
        ShowSum(value3:=8, value2:=7, value1:=6)                           ' (3)
        '
        ShowSum(4, value3:=5)                                              ' (4)
        '
        Console.ReadLine()
    End Sub
    Sub ShowSum(ByVal value1 As Integer, _
                Optional ByVal value2 As Integer = 2, _
                Optional ByVal value3 As Integer = 3)
        Console.WriteLine(value1 + value2 + value3)
    End Sub
End Module
Module Example5
    Sub Main()
        Dim numbers As Integer() = {1, 2, 3, 4, 5}
        PrintArray(numbers)
        '
        Dim words As String() = {"Hello", "World"}
        PrintArray(words)
        '
        Dim dates As Date()
        PrintArray(dates)                                                  ' (1)
        '
        PrintArray(Nothing)
        '
        Console.ReadLine()
    End Sub
    Sub PrintArray(ByVal values As Array)
        If values IsNot Nothing Then
            For Each element As Object In values
                Console.Write(element & " ")
            Next
            Console.WriteLine()
        Else
            Console.WriteLine("No array.")
        End If
    End Sub
End Module
Module Example6
    Sub Main()
        Dim object1 As Object
        '
        object1 = 5
        Console.WriteLine(object1)
        Console.WriteLine(object1 + 10)
        '
        object1 = "Hello"
        Console.WriteLine(object1)
        Console.WriteLine(object1 & " World !")
        '
        object1 = True
        Console.WriteLine(object1)
        Console.WriteLine(object1 AndAlso False)
        '
        Console.ReadLine()
    End Sub
End Module
Module Example7
    Sub Main()
        Dim values1 As Integer() = {1, 2, 3}
        Dim values2 As Integer() = {4, 5, 6}
        Dim values3 As Integer() = values1
        Dim values4 As Array = values2
        '
        Console.WriteLine(values1 IsNot values2)
        Console.WriteLine(values1 Is values3)
        Console.WriteLine(values1 IsNot values4)
        Console.WriteLine()
        '
        Console.WriteLine(values2 IsNot values1)
        Console.WriteLine(values2 IsNot values3)
        Console.WriteLine(values2 Is values4)
        '
        Console.ReadLine()
    End Sub
End Module
Module Example8
    Sub Main()
        Dim values As Integer() = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
        Example5.PrintArray(values)
        '
        DoubleIntegerValues(values, 5)
        Example5.PrintArray(values)
        '
        ResizeIntegerArray(values, 20)
        Example5.PrintArray(values)
        '
        Console.ReadLine()
    End Sub
    Sub DoubleIntegerValues(ByVal values As Integer(), ByVal count As Integer)
        For index As Integer = 0 To count - 1
            values(index) *= 2
        Next
    End Sub
    Sub ResizeIntegerArray(ByRef values As Integer(), ByVal capacity As Integer)
        ReDim values(capacity - 1)
    End Sub
End Module
Module Example9
    Sub Main()
        Dim values As Integer()
        Example5.PrintArray(values)
        '
        values = GetIntegerArray(10)
        Example5.PrintArray(values)
        '
        Console.ReadLine()
    End Sub
    Function GetIntegerArray(ByVal capacity As Integer) As Integer()
        Dim integerArray(capacity - 1) As Integer
        GetIntegerArray = integerArray
    End Function
End Module
Module Example10
    Sub Main()
        Console.WriteLine(GetSum(1, 2, 3, 4, 5))
        Console.WriteLine(GetSum(1, 2, 3, 4))
        Console.WriteLine(GetSum(1, 2, 3))
        Console.WriteLine(GetSum(1, 2))
        Console.WriteLine(GetSum(1))
        Console.WriteLine(GetSum())                                        ' (1)
        '
        Console.ReadLine()
    End Sub
    Function GetSum(ByVal ParamArray values As Integer()) As Integer
        If values IsNot Nothing Then
            For Each value As Integer In values
                GetSum += value
            Next
        End If
    End Function
End Module
Module Example11
    Sub Main()
        Dim values As Integer() = {1, 2, 3, 4, 5}
        Console.WriteLine(Example10.GetSum(values))
        '
        values = Nothing
        Console.WriteLine(Example10.GetSum(values))                        ' (1)
        '
        Console.ReadLine()
    End Sub
End Module
Module Exercise2Task
    Sub Main()
        Console.WriteLine(Exercise2Solution.GetConcatenation("abc", "def", _
                                                             "ghi"))
        Console.WriteLine(Exercise2Solution.GetConcatenation("abc", "def"))
        Console.WriteLine(Exercise2Solution.GetConcatenation("abc"))
        Console.WriteLine(Exercise2Solution.GetConcatenation())
        '
        Dim words As String() = {"abc", "def", "ghi"}
        Console.WriteLine(Exercise2Solution.GetConcatenation(words))
        '
        words = Nothing
        Console.WriteLine(Exercise2Solution.GetConcatenation(words))
        '
        Console.ReadLine()
    End Sub
End Module
Module Exercise2Solution
    Function GetConcatenation(ByVal ParamArray words As String()) As String
        If words IsNot Nothing Then
            For Each word As String In words
                GetConcatenation &= word
            Next
        End If
    End Function
End Module
Module Exercise3Task
    Sub Main()
        Dim values As Integer() = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
        Example5.PrintArray(values)
        '
        Dim count As Integer = 5
        Dim valuesCopy As Integer()
        valuesCopy = Exercise3Solution.GetIntegerArrayCopy(values, count)
        Example5.PrintArray(valuesCopy)
        '
        Dim factor As Integer = 4
        count = 3
        Exercise3Solution.MultiplyIntegerValues(valuesCopy, count, factor)
        '
        Example5.PrintArray(values)
        Example5.PrintArray(valuesCopy)
        '
        count = 6
        Exercise3Solution.MultiplyIntegerValues(values, count)
        '
        Example5.PrintArray(values)
        Example5.PrintArray(valuesCopy)
        '
        Console.ReadLine()
    End Sub
End Module
Module Exercise3Solution
    Function GetIntegerArrayCopy(ByVal values As Integer(), _
                                 ByVal count As Integer) As Integer()
        Dim valuesCopy(count - 1) As Integer
        For index As Integer = 0 To count - 1
            valuesCopy(index) = values(index)
        Next
        GetIntegerArrayCopy = valuesCopy
    End Function
    Sub MultiplyIntegerValues(ByVal values As Integer(), _
                              ByVal count As Integer, _
                              Optional ByVal factor As Integer = 2)
        For index As Integer = 0 To count - 1
            values(index) *= factor
        Next
    End Sub
End Module

' Visit www.studyvb.com for more examples.  Copyright 2003-2008 De Wolf.