Declare Function with passed array

[Richard]

I am having trouble finding out how to write a "Declare Function" statement that specifies an array as a passed parameter. The following code runs ok but if I uncomment the "Declare Function two(... " line it gives me "error 55, type missmatch" at the "Function two(..." line later on.
How should I write the "Declare Function two(... )" line?

Code: Select all

Declare Function one(As Double) As Double
Function one (x As Double) As Double
    one = x
End Function
Print one(1)

' Declare Function two(As Integer, As Double) As Double

Function two ( n As Integer, x() As Double) As Double
    two = x(n)
End Function

Dim As Double x2(3)
Dim As Integer nn = 2
x2(nn) = 2
Print two( nn, x2(nn) )

Sleep

[D.J.Peters]

Code: Select all

Declare Function one(x As Double) As Double
Declare Function two(x() As Double,n As Integer) As Double

Function one (x As Double) As Double
    one = x
End Function
Print one(1)


Function two (x() As Double,n as integer) As Double
    two = x(n)
End Function

Dim As Double x2(3)
Dim As Integer n = 2
x2(n) = 2
Print two(x2(n),n)

Sleep

[Richard]

D.J.Peters, Thanks for that. To put the empty brackets in to specify an array needs any dummy variable name. The word array seems to work and makes the meaning obvious.
So simple.

Code: Select all

Declare Function two( As Integer, array() As Double) As Double

[cha0s]

You can also write it like "two(x2(), n)". I'm honestly surprised that it accepts an indexed array as an arg.

[Richard]

Since arrays are now passed Byref and might one day be passed Byval, I am being explicit by declaring:

Code: Select all

Declare Function x ( Byref array() As Integer) as Integer
' the above gives a compile error 56 - illegal specification
Declare Function x ( array() As Integer) as Integer ' but this works OK 

Is it possible to allow me to be explicit when passing arrays to functions and subs ?

[anonymous1337]

ByRef Arrays = Surprise to me. They're ByDesc, aren't they? They've always been. I never heard about such a change!

[cha0s]

Yeah, they aren't passed byref as other variables are, a reference to their descriptor is passed so it's more like "bydesc". Been that way since FB was created, as far as I know.

[Richard]

But there is no ByDesc keyword available!

[cha0s]

That's because FreeBASIC keeps the dirty details hidden from you. :P

It would be nice to have the option to pass arrays byval, but that would be slow as $%#@ for huge arrays.

Next thing you know, people will ask to treat byref variables like the pointers they really are! ;)