Functions in VB.net – Definition of Functions in VB.net

Functions in VB.net

The functions in VB.net 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 add multiple functions to a program to carry out different functionalities. By minimizing duplicate code, the method also helps with code reuse. For instance, we can easily write a function and call it whenever necessary if we need to employ the same functionality across a program.

In order for you to test your VB.net Code provided in this lesson, you must test the code in your code editor. But if you wish to run this code online, we also have an Online Compiler in VB.net for you to test your VB.net Code for free.

VB.net Function Definition

The name, parameters, and body of a function are declared using the Function statement.

Syntax for the Function Statement in VB.net:

'syntax for the function statement'

[Modifiers] Function FunctionName [(ParameterList)] As ReturnType
[Statements]
End Function

1. Modifiers

define the function’s access level; options include Public, Private, Protected, Friend, and Protected Friend. You should also include details on overloading, overriding, sharing, and shadowing.

2. FunctionName

Indicates the name of the function that should be unique.

3. ParameterList

Specifies the list of the parameters.

4. ReturnType

specifies the data type of the variable the function returns

The function FindMax in the following code snippet returns the greater of two integer values given two values.

Function FindMax(ByVal num1 As Integer, ByVal num2 As Integer) As Integer
   ' local variable declaration */
   Dim result As Integer
   
   If (num1 > num2) Then
      result = num1
   Else
      result = num2
   End If
   FindMax = result
End Function

Function Returning a Value in VB.net

In VB.Net, a function has two different ways to return a value to the caller code.

  • By using the return statement
  • By assigning the value to the function name

The following example demonstrates using the FindMax function:

Module myfunctions
   Function FindMax(ByVal num1 As Integer, ByVal num2 As Integer) As Integer
      ' local variable declaration */
      Dim result As Integer
      
      If (num1 > num2) Then
         result = num1
      Else
         result = num2
      End If
      FindMax = result
   End Function
   Sub Main()
      Dim a As Integer = 100
      Dim b As Integer = 200
      Dim res As Integer
      
      res = FindMax(a, b)
      Console.WriteLine("Max value is : {0}", res)
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

Max value is : 200

Test your Code Here!

Recursive Function in VB.net

A function in VB.net is referred to as recursive if it keeps calling itself until the specified condition is met. Numerous mathematical problems, such producing the Fibonacci series and computing the factorial of a number, can be solved using recursive functions.

Following is an example that calculates factorial for a given number using a Recursive function in VB.net.

Module myfunctions
   Function factorial(ByVal num As Integer) As Integer
      ' local variable declaration */
      Dim result As Integer
      
      If (num = 1) Then
         Return 1
      Else
         result = factorial(num - 1) * num
         Return result
      End If
   End Function
   Sub Main()
      'calling the factorial method
      Console.WriteLine("Factorial of 6 is : {0}", factorial(6))
      Console.WriteLine("Factorial of 7 is : {0}", factorial(7))
      Console.WriteLine("Factorial of 8 is : {0}", factorial(8))
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

Factorial of 6 is : 720
Factorial of 7 is : 5040
Factorial of 8 is : 40320

Test your Code Here!

Param Arrays in VB.net

You might not always be certain of the number of arguments supplied as a parameter when declaring a function or sub process. These situations call for the use of VB.Net param arrays (also known as parameter arrays).

Example Program of Param Arrays in VB.net:

Module myparamfunc
   Function AddElements(ParamArray arr As Integer()) As Integer
      Dim sum As Integer = 0
      Dim i As Integer = 0
      
      For Each i In arr
         sum += i
      Next i
      Return sum
   End Function
   Sub Main()
      Dim sum As Integer
      sum = AddElements(512, 720, 250, 567, 889)
      Console.WriteLine("The sum is: {0}", sum)
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

The sum is: 2938

Test your Code Here!

Passing Arrays as Function Arguments in VB.net

In VB.net, you can pass an array as a function argument.

Example Program for Passing Arrays as a Function Arguments in VB.net.

Module arrayParameter
   Function getAverage(ByVal arr As Integer(), ByVal size As Integer) As Double
      'local variables
      Dim i As Integer
      Dim avg As Double
      Dim sum As Integer = 0
      
      For i = 0 To size - 1
         sum += arr(i)
      Next i
      avg = sum / size
      Return avg
   End Function
   Sub Main()
      ' an int array with 5 elements '
      Dim balance As Integer() = {1000, 2, 3, 17, 50}
      Dim avg As Double
      'pass pointer to the array as an argument 
      avg = getAverage(balance, 5)
      ' output the returned value '
      Console.WriteLine("Average value is: {0} ", avg)
      Console.ReadLine()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

Average value is: 214.4

Test your Code Here!

Summary

A Function returns a value as opposed to a Sub. If we don’t have a return value, we must use a Sub. We must return this value. We are able to assign to a Function’s output.


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