Procedure/Function Examples

Example : A program in VB .Net 2013 to show a Subroutine/Sub Procedure.

Module Module1
    Dim x, y, z As Integer
    Sub Output()
        x = 10
        y = 20
        z = x + y
        'Console.WriteLine("The addition result is = " & z)
        Console.WriteLine("The addition result of " & x & " and " & y & " is = " & z)
    End Sub

    Sub Main()
        Output()
        Console.ReadKey()
    End Sub
End Module

Output: The addition result of 10 and 20 is = 30

NB: Subroutine(sub) procedure never return a value like a Function in VB .Net.

---------------  OR  ---------------

Imports System
Module Module1
    Dim x, y, z As Integer
    Sub Output()
        Console.Write("Enter First Value = ")
        x = Console.ReadLine()
        Console.Write("Enter Second Value = ")
        y = Console.ReadLine()
        z = x + y
        Console.WriteLine("The addition result is = " & z)
    End Sub

    Sub Main()
        Output()
        Console.ReadKey()
    End Sub
End Module

---------------  OR  ---------------

Imports System
Module Module1
    Dim x1, y1, z As Integer
    Sub Output(ByVal x2 As Integer, ByVal y2 As Integer) 'Parameterized Subroutine.
        x1 = x2
        y1 = y2
        z = x1 + y1
        Console.WriteLine("The addition result is = " & z)
    End Sub

    Sub Main()
        Output(10, 20)
        Console.ReadKey()
    End Sub
End Module

---------------  OR  ---------------

Imports System
Module Module1
    
    Sub Output(ByVal x2 As Integer, ByVal y2 As Integer) 'Parameterized Subroutine.
        
        Console.WriteLine("The first value is = " & x2)
        Console.WriteLine("The second value is = " & y2)
    End Sub

    Sub Main()
        Output(10, 20)
        Console.ReadKey()
    End Sub

End Module

---------------  OR  ---------------

Imports System
Module Module1
    Dim x, y, z As Integer
    Sub Output(ByVal a As Integer, ByVal b As Integer)
        z = a + b
        Console.WriteLine("The addition result is = " & z)
    End Sub

    Sub Main()
        Console.Write("Enter First Value = ")
        x = Console.ReadLine()
        Console.Write("Enter Second Value = ")
        y = Console.ReadLine()
        Output(x, y)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show a Parameterized Subroutine Procedure.

Module Module1
    Sub StringMessage(ByVal name As String)
        Console.WriteLine("Hello, " & name)
    End Sub

    Sub Main()
        StringMessage("India")
        Console.ReadKey()
    End Sub

End Module

Example : A program in VB .Net 2013 to show a  Non-Parameterized String value using a Subroutine Procedure.

Module Module1
    Sub Message()
        Console.WriteLine("Hello India")
    End Sub

    Sub Main()
        Message()
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show Optional and Default Parameters using Subroutine Procedure.

Module Module1
    Sub Example(Optional ByVal name As String = "India")
        Console.WriteLine("Hello, " & name)
    End Sub

    Sub Main()
        Example()             ' Output: Hello, India [default parameter]
        Example("World")      ' Output: Hello, World
        Console.ReadKey()
    End Sub
End Module

NB:
Parameters in a sub procedure can be optional and can have default values.

Example : A program in VB .Net to show the Exit Sub Statement using a  Sub Procedure.

Module Module1
    Sub CheckAge(ByVal age As Integer)
        If age < 18 Then
            Console.WriteLine("Not Eligible for Vote!")
            Exit Sub
        End If
        Console.WriteLine("Eligible for Vote")
    End Sub

    Sub Main()
        CheckAge(50)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net 2013 to show the ByVal (Call by Value) Statement using a Sub Procedure.

Module Module1
    ' Define a Sub that uses ByVal
    Sub Calculation(ByVal num As Integer)
        Dim x As Integer = num
        Console.WriteLine("The value after procesing is : " & x)
    End Sub

    Sub Main()
        ' Declare a variable
        Dim Value As Integer = 20

        ' Call the Sub
        Calculation(Value)

        ' Print the original value after the Subroutine call
        Console.WriteLine("Original value before processing : " & Value)
        Console.ReadKey()
    End Sub
End Module

Output:
The value after procesing is : 20
Original value before processing : 20

Example : A program in VB .Net to show the ByRef (Call by Reference) Statement using a Sub Procedure.

Module Module1
    ' Define a Sub that uses ByRef statement
    Sub UpdateValue(ByRef num As Integer)
        ' Modify the original variable
        num = num + 50
        Console.WriteLine("Value inside the Sub (ByRef): " & num)
    End Sub

    Sub Main()
        ' Declare an integer variable
        Dim originalValue As Integer = 50

        ' Print the original value before calling/using the Sub
        Console.WriteLine("Original value before Sub call: " & originalValue)

        ' Call the Sub with ByRef
        UpdateValue(originalValue)

        ' Print the original value after calling the Sub
        Console.WriteLine("Original value after Sub call: " & originalValue)
        Console.ReadKey()
    End Sub
End Module

Output:
Original value before Sub call: 50
Value inside the Sub (ByRef): 100
Original value after Sub call: 100

Example : A program in VB .Net 2013 to show the Exit Function Statement using a Function Procedure.

Module Module1
    Function CheckAge(ByVal age As Integer)
        If age < 18 Then
            Console.WriteLine("Not Eligible for Vote!")
            Exit Function
        End If
        Console.WriteLine("Eligible for Vote")
    End Function

    Sub Main()
        CheckAge(10)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show No Parameter and No Return using a Function Procedure.

Module Module1
    Dim x As Integer = 100
    Function Output()
        Console.WriteLine(x)
        Return 0
        'Return 1
        'Return 10
    End Function

    Sub Main()
        Output()
        Console.ReadKey()
    End Sub
End Module

Output: 100

---------------  OR  ---------------

Module Module1
    Function Message()
        Console.WriteLine("Hello India")
        Return 1
    End Function

    Sub Main()
        Message()
        Console.ReadKey()
    End Sub
End Module

NB: Function must Return a value either 0,1 or numeric output or any other numeric value in VB .Net 2013. Only Return statement not allowed.

Example : A program in VB .Net to show No Parameter and With Return using a Function Procedure.

Module Module1
    Function Calculation()
        Dim x = 10, y = 20, z As Integer
        z = x + y
        Return z
    End Function

    Sub Main()
        Console.WriteLine("The addition result is = " & Calculation())
        Console.ReadKey()
    End Sub
End Module

---------------  OR  ---------------

Module Module1
    Dim k As Integer
    Function Calculation()
        Dim x = 10, y = 20, z As Integer
        z = x + y
        Return z
    End Function

    Sub Main()
        k = Calculation()
        Console.WriteLine("The addition result is = " & k)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show With Parameter and No Return using a Function Procedure.

Module Module1
    Function Calculation(ByVal x As Integer, ByVal y As Integer)
        Dim z As Integer
        z = x + y
        Console.WriteLine("The addition result is = " & z)
    End Function

    Sub Main()
        Calculation(10, 20)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show With Parameter and With Return using a Function Procedure.

Module Module1
    Dim k As Integer
    Function Calculation(ByVal x As Integer, ByVal y As Integer)
        Dim z As Integer
        z = x + y
        Return z
    End Function

    Sub Main()
        k = Calculation(10, 20)
        Console.WriteLine("The addition result is = " & k)
        Console.ReadKey()
    End Sub
End Module

---------------  OR  ---------------

Module Module1
    Function Calculation(ByVal x As Integer, ByVal y As Integer)
        Dim z As Integer
        z = x + y
        Return z
    End Function

    Sub Main()
        Console.WriteLine("The addition result is = " & Calculation(10, 20))
        Console.ReadKey()
    End Sub
End Module

---------------  OR  ---------------

Module Module1
    Dim k, a, b As Integer
    Function Calculation(ByVal x As Integer, ByVal y As Integer)
        Dim z As Integer
        z = x + y
        Return z
    End Function

    Sub Main()
        Console.Write("Enter First Value = ")
        a = Console.ReadLine()
        Console.Write("Enter Second Value = ")
        b = Console.ReadLine()

        k = Calculation(a, b)
        Console.WriteLine("The addition result is = " & k)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show a Recursive Function using a Function Procedure.

Module Module1
    Function Factorial(ByVal n As Integer) As Integer
        If n = 0 Then
            Return 1
        Else
            Return n * Factorial(n - 1)
        End If
    End Function

    Sub Main()
        Dim result As Integer = Factorial(5)
        Console.WriteLine("The factorial result is: " & result)
        Console.ReadKey()
    End Sub
End Module

Example : A program in VB .Net to show a Shared Function using a Function Procedure.

Module Module1
    Class Example
        Shared Function Square(ByVal num As Integer) As Integer
            Return num * num
        End Function
    End Class

    Sub Main()
        Dim result As Integer = Example.Square(5)
        Console.WriteLine("The square value is = " & result)
        Console.ReadKey()
    End Sub
End Module