Procedures (Functions and Subroutines)

Procedures are named blocks of code that perform a specific task. In Visual Basic .NET, procedures are implemented as either Sub procedures (subroutines) or Function procedures. Subroutines perform an action but do not return a value, while functions perform an action and return a value.

Sub Procedures (Subroutines)

Sub procedures are used to perform actions. They do not return a value to the calling code. You call a Sub procedure using its name.

Syntax

Sub ProcedureName(Optional arg1 As DataType, Optional arg2 As DataType)
    ' Code to execute
End Sub

Example

Sub GreetUser(ByVal userName As String)
    Console.WriteLine("Hello, " & userName & "!")
End Sub

' Calling the Sub procedure
GreetUser("Alice")

Function Procedures

Function procedures perform actions and return a single value to the calling code. The return type of the function is specified after the parameter list.

Syntax

Function FunctionName(Optional arg1 As DataType, Optional arg2 As DataType) As ReturnDataType
    ' Code to execute
    FunctionName = "Some Value" ' Assign the return value
End Function

Example

Function AddNumbers(ByVal num1 As Integer, ByVal num2 As Integer) As Integer
    AddNumbers = num1 + num2
End Function

' Calling the Function procedure
Dim result As Integer
result = AddNumbers(5, 10)
Console.WriteLine("The sum is: " & result) ' Output: The sum is: 15

Parameter Passing

Parameters can be passed to procedures in two ways:

• ByVal: A copy of the variable is passed. Changes made to the parameter within the procedure do not affect the original variable. This is the default.
• ByRef: A reference to the variable is passed. Changes made to the parameter within the procedure affect the original variable.