what does := mean in visual basic .net (console application)

[jayxxxx]

the code was for an overload method
console.writeline(totalprice(price:=totalprice))
the name of the method was totalprice
the parameter for it was price

but I didn't know what does := between the parameter and the function.

[SioSio]

":=" isNamed arguments are the function of the method caller

'Ex.
 
Public Function SampleMethod1(Optional x As Integer = 0,
                              Optional y As Integer = 0,
                              Optional z As Integer = 0) As Integer
  Return x + y * 2 + z * 3
End Function
 
Console.WriteLine("SampleMethod1(1,2,3):{0}", SampleMethod1(1, 2, 3))
' Output：SampleMethod1(1,2,3)=14
Console.WriteLine("SampleMethod1(1,2,3):{0}", SampleMethod1(x:=1, y:=2, z:=3))
' Output：SampleMethod1(1,2,3)=14

[IronRazer]

Have a look at the msdn link below, it will explain in detail what the := symbol is used for.

Passing Arguments by Position and by Name

Basically, it is used to set the value of the arguments in your call to a Sub/Function by their parameter Names instead of setting them in their specified order, separated by commas. You will see the := used with subs and functions that have several Optional parameters.

For example, this example sub has three Optional parameters, a, b, and c.

    Private Sub DoSomething(Optional a As Integer = 0, Optional b As Integer = 0, Optional c As Integer = 0)
 
    End Sub
 

You can call this sub by specifying the name of parameter you want to set. Suppose I only want to set the c parameter to a value of 10 when I call it. I can do this...

DoSomething(c:=10)

On the other hand, you could call this sub and separate each parameter with a comma like below, and get the same result.

DoSomething(,, 10)