What does := mean in vb.net?

vb.net colon-equals
Scott picture Scott · Oct 29, 2010 · Viewed 7.5k times · Source

We have this method call:

SendAck(AppData:=AppData, Status:=Status, StatusMessage:=StatusMessage, IsApplication:=IsApplication)

And here is the definition:

Private Sub SendAck(ByVal AppData As XDocument, ByVal Status As Boolean, ByVal StatusMessage As String, ByVal IsApplication As Boolean)

Why does the call have the parameters with the ":=". I'm just curious.

Answer

JaredPar picture JaredPar · Oct 29, 2010

The ":=" in VB.Net is used to pass a function argument by name. The default is by position. It allows for parameters to be called in any order and determines the positioning based on name matches.

For example

Sub Example(ByVal param1 as Integer, ByVal param2 As Integer) 
  Console.WriteLine("{0} - {1}", param1, param2)
End Sub

Example(param2:=42, param1:=1) ' Prints "1 - 42"
Example(42, 1)                 ' Prints "42 - 1"

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