Dim, Redim At

[Chris Holbrook]

Two questions:

1. Is it acceptable to REDIM...AT to a different AT address from the previous one?

2. REDIM without an initial DIM sometimes won't compile. IS it OK to DIM without the AT qualifier then REDIM AT?

[John Gleason]

The code below shows yes, and yes to the 2 questions. I didn't have a problem compiling with REDIM only, have you got a code example that won't compile?

#COMPILE EXE
#DIM ALL

FUNCTION PBMAIN () AS LONG

    LOCAL myString AS STRING, ii AS LONG, ptrMyString AS BYTE PTR
    myString = SPACE$(5000000)
    ptrMyString = STRPTR(myString)
    FOR ii = 1 TO 5000000
       @ptrMyString = ii MOD 256 'long repeating string
       INCR ptrMyString
    NEXT
       
    REDIM a(1000000) AS LONG
    REDIM a(1000000) AS LONG AT STRPTR(myString)
    ? STR$(a(500000))
    REDIM a(1000000) AS LONG AT STRPTR(myString) + 500000
    ? STR$(a(500000))

END FUNCTION

[Chris Holbrook]

Yes, you're probably right. It seemed to work for me too, but I got a bit suspicious of it after making a GPF go away by using an initial DIM. Next time I will keep the original code, so don't ask!

The application has been rewritten without using a DIM/REDIMed array.

I don't like arrays very much.

[Michael Mattias]

REDIM without an initial DIM sometimes won't compile. IS it OK to DIM without the AT qualifier then REDIM AT?

 FUNCTION Foo( params) as Something

  LOCAL  X() AS whatever
  ....
.....
.....
    REDIM X (number) AT address

MCM

[Michael Mattias]

Explanation:

LOCAL  X() AS whatever

Tells compiler, which reads top to bottom, "Whenever you see the symbol 'X' in this procedure it means an array of whatevers"

NOte: you may need to physically place a REDIM statement prior to any use of X() in the procedure to avoid an 'array not dimensioned' error. (I never figured out the actual rules used). But that's easy enough...

FUNCTION Foo ( ......
 LOCAL X() AS whatever
 LOCAL  I, J, K AS LONG
 ...
' == END VARIABLE DECLARATIONS, START CODE  ====
  REDIM X(0) 

 ' REAL CODE STARTS HERE
....

MCM