Array as Parameters

[Joe Speroni]

I want to write a function that has an array as a parameter.
Starting with the working scalar example,

FUNCTION P(b AS LONG) AS LONG:MSGBOX STR$(b):END FUNCTION
FUNCTION PBMAIN() AS LONG
LOCAL a AS LONG
a=4:P(a)
END FUNCTION

here is one of the many examples I tried that did not work.

FUNCTION P(b() AS LONG) AS LONG:MSGBOX STR$(b(4)):END FUNCTION
FUNCTION PBMAIN() AS LONG
DIM a(4) AS LONG:a(4)=-4:P(a())
END FUNCTION

There is no documentation on how to pass arrays to a function.
The old DOS PB compiler did have it. Perhaps it is no
longer permitted in the CC and DLL verions?

Anyone have any recommendations?

BTW it was a pleasant surprise to find out that MSGBOX worked
as the PRINT statement in the DLL compiler when executing
from a DOS prompt. It would be useful to include that info
in the manual under PRINT (not supported, see MSGBOX; then
include an explanation in the REMARKS section of MSGBOX).

[Florent Heyworth]

Hi Joe

passing arrays BYREF works fine - the only problem you've got is that you declare P() as a function and disregard its return value (you didn't specify one).

This works:

FUNCTION P(b() AS LONG) AS LONG
    MSGBOX STR$(b(4))
END FUNCTION

FUNCTION PBMAIN() AS LONG
    DIM a(4) AS LONG
    a(4)=-4
    'Need to use CALL Syntax or simply P a()
    CALL P(a())
    P a()
END FUNCTION

Cheers

Florent

[Borje Hagsten]

FUNCTION P() is expected to return something. Either make it a SUB or use
"lRes& = P(a())" or even "CALL P(a())". The following works fine:

#COMPILE EXE
 
FUNCTION P(b() AS LONG) AS LONG
  MSGBOX STR$(b(4))
END FUNCTION
 
FUNCTION PBMAIN() AS LONG
  DIM a(4) AS LONG
  a(4)=-4
  CALL P(a()) 'or lRes& = P(a())
END FUNCTION

[Joe Speroni]

Florent Heyworth and Borje Hagsten

Fellows, thanks. It never occured to me there was a difference between
P(a()) and CALL P(a()) [a.k.a. P a(), which I prefer).

Had I looked at the CALL documentation I would have found an example of
a call of a function with an array as a parameter. And looking further
afield under the memeory layout for arrays's, the functions LBOUND
and UBOUND which implied the existence of array parameters.

Thanks for your help.