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

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

A Function can return a value from itself. For example

Code:

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

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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

Code:

---

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

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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.

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.

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

Sub
Function