Difference between Sub and Function in Visual Basic and VB.Net

[Bellamy]

What's the difference between a Sub and a Function in Visual Basic ?

[MindSpace]

A Function can return a value from itself. For example

Public Function Sum(ByVal a As Integer, _
ByVal b As Integer) As Integer
Return a + b
End Function

Then you can use this Function as follows

Dim result As Integer = Sum(2, 4)

On the other hand a Sub can not return a value from itself. It must use a
ByRef parameter to get a result. For example

Public Sub SumSub(ByVal a As Integer, _
ByVal b As Integer) As Integer)
Dim theSum As Integer = a + b
End Sub

This has no way of returning the result and using this like

Dim answer As Integer = SumSub(2, 4)

will generate a complile time error.

[Modifier]

The Sub statement is used to execute one or more lines of code, period.

The Function statement is used to execute one or more lines of code AND return a value to the caller.

Use a Sub when you do not need to return a value to the calling code. Use a Function when you need to return a value.

[Praetor]

To learn more about Visual Basic.NET Sub and Function statements click these links:

Sub
Function