VB.NET Functions

In VB.NET, the function is a separate group of codes that are used to perform a specific task when the defined function is called in a program. After the execution of a function, control transfer to the main() method for further execution. It returns a value. In VB.NET, we can create more than one function in a program to perform various functionalities. The function is also useful to code reusability by reducing the duplicity of the code. For example, if we need to use the same functionality at multiple places in a program, we can simply create a function and call it whenever required.

Defining a Function

The syntax to define a function is:

  [Access_specifier ] Function Function_Name [ (ParameterList) ] As Return_Type  [ Block of Statement ]  Return return_val  End Function  

Where,

Access_Specifier: It defines the access level of the function such as public, private, or friend, Protected function to access the method.
Function_Name: The function_name indicate the name of the function that should be unique.
ParameterList: It defines the list of the parameters to send or retrieve data from a method.
Return_Type: It defines the data type of the variable that returns by the function.

The following are the various ways to define the function in a VB.NET.

  Public Function add() As Integer  ‘ Statement to be executed  End Function    Private Function GetData( ByVal username As String) As String  ‘ Statement to be executed  End Function    Public Function GetData( ByVal username As String, ByVal userId As Integer) As String  ‘ Statement to be executed  End Function  

Example: Write a program to find the sum and subtraction of two numbers using the function.

Find_Sum.vb

  Imports System  Module Find_Sum      ‘ Create the SumOfTwo() Function and pass the parameters.      Function SumOfTwo(ByVal n1 As Integer, ByVal n2 As Integer) As Integer          ‘ Define the local variable.          Dim sum As Integer = 0          sum = n1 + n2          Return sum      End Function      Function SubtractionOfTwo(ByVal n1 As Integer, ByVal n2 As Integer) As Integer          ‘ Define the local variable.          Dim subtract As Integer          subtract = n1 – n2          Return subtract      End Function      Sub Main()          ‘ Define the local variable a and b.          Dim a As Integer = 50          Dim b As Integer = 20          Dim total, total1 As Integer          Console.WriteLine(” First Number is : {0}”, a)          Console.WriteLine(” Second Number is : {0}”, b)          total = SumOfTwo(a, b) ‘call SumOfTwo() Function          total1 = SubtractionOfTwo(a, b) ‘call SubtractionOfTwo() Function          Console.WriteLine(” Sum of two number is : {0}”, total)          Console.WriteLine(” Subtraction of two number is : {0}”, total1)          Console.WriteLine(” Press any key to exit…”)          Console.ReadKey()      End Sub  End Module  

Output:

VB.NET Functions

In the above example, we have defined a SumOfTwo() and SubtractionOfTwo() function to add and subtract two predefined numbers. When the functions are called in the main() method, each function is executed and returns the sum and subtraction of two numbers, respectively.

Example: Write a program to reverse a number and check whether the given number is palindrome or not.

Palindrome.vb

  Imports System  Module Palindrome      ‘ Define a reverse() function       Function reverse(ByVal num As Integer) As Integer          ‘ Define the local variable          Dim remain As Integer          Dim rev As Integer = 0          While (num > 0)              remain = num Mod 10              rev = rev * 10 + remain              num = num / 10          End While          Return rev      End Function      Sub Main()          ‘ Define the local variable as integer          Dim n, num2 As Integer          Console.WriteLine(” Enter a number”)          n = Console.ReadLine() ‘Accept the number          num2 = reverse(n) ‘ call a function          Console.WriteLine(” Reverse of {0} is {1}”, n, num2)            If (n = reverse(n)) Then              Console.WriteLine(” Number is a Palindrome”)          Else              Console.WriteLine(” Number is not a Palindrome”)          End If          Console.WriteLine(“Press any key to exit…”)          Console.ReadKey()      End Sub  End Module  

Output:

VB.NET Functions

Recursive Function

When a function calls itself until the defined condition is satisfied, it is known as a recursive function. A recursive function is useful for solving many mathematical tasks such as generating the Fibonacci series, the factorial of a number, etc.

Let’s create a program to calculate the factorial of a number using the recursive function.

Factorial_function.vb

  Imports System  Module Factorial_function      ‘ Create a Fact() function      Function Fact(ByVal num As Integer) As Integer          If (num = 0) Then              Return 0          ElseIf (num = 1) Then              Return 1          Else              Return num * Fact(num – 1)          End If      End Function      Sub Main()          ‘ Define the local variable as integer          Dim n, f As Integer          Console.WriteLine(” Enter the number you want to calculate factorial”)          n = Console.ReadLine() ‘Accept a number          f = Fact(n) ‘call Fact() function          Console.WriteLine(” Factorial is : {0}”, f)          Console.WriteLine(” Press any key to exit…”)          Console.ReadKey()      End Sub  End Module  

Output:

VB.NET Functions

Passing Array as a Parameter

Let’s create a program that parses an array as a pass parameters in a function.

Array_Parameter.vb

  Imports System  Module array_Parameter      Function AddPara(ByVal Arr As Integer(), ByVal size As Integer) As Double          ‘Declare a local variable.            Dim i As Integer          Dim avg As Double          Dim Sum As Integer = 0            For I = 0 To size – 1              Sum = Sum + Arr(i)          Next          avg = Sum / size          Return avg      End Function      Sub Main()          Dim arrays As Integer() = {50, 10, 20, 5, 4, 25}          Dim getAvg As Double          getAvg = AddPara(arrays, 6)          Console.WriteLine(“Average sum of array element is {0}”, getAvg)          Console.WriteLine(” Press any key to exit…”)          Console.ReadKey()      End Sub  End Module  

Output:

VB.NET Functions

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VB.NET Functions

VB.NET Functions

Defining a Function

Recursive Function

Passing Array as a Parameter

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