Delphi pass static array as var in function parameter

Question

I can't seem to find any information or understanding why the compiler throws error " E2029 'OF' expected but '[' found " when I try to use static array instead of dynamic.

I'm calling functions form a DLL file, so I'm having this code:

function RetrieveDSOData(whatchannels: uchar; var DSOCH1, DSOCH2: array of double; 
var LADATA: array of ushort; Nth_Sample: uchar): longint; 
stdcall; external 'E_l80.dll';

This compiles ok, but I have AV errors in DLL files, and since I suspect that the issue is the dynamic array does not get size specified, I wanted to throw it a static array.

But, if I write the above function with

DSOCH1, DSOCH2: array [0..31] of double;

I get the compiler error mentioned above.

Additional info: I have instructions on how to use this DLL written for C, and since I barely know it, I might be missing something else around these arrays: This is the original function:

long RetrieveDSOData(unsigned char whatchannels, double *DSOCH1,
double *DSOCH2, unsigned short *LADATA, unsigned char Nth_Sample)

with explanations like this:

*DSOCHX: A pointer to an array of points from the DSO channels.
*LADATA: A pointer to an array of LA data

Any help would be appreciated. (and please do not edit this question just for deleting this last sentence... makes no sense...)

Have you tried defining your own type and using that instead? type TMyArray = array[0..31] of Double; — Jerry Dodge
– Jerry Dodge, Commented May 16, 2015 at 0:12
You need to create a type alias TMyArray = array[0..31] of double and then use TMyArray. — Graymatter
– Graymatter, Commented May 16, 2015 at 0:13
True. The hint given (as well as in the answer) does get me through compiler, however now the app hangs at calling the function... :( Do you happen to help me out on the second-part of the question...? — That Marc
– That Marc, Commented May 16, 2015 at 0:50

Ken White · Accepted Answer · 2015-05-16 02:29:07Z

7

Define a type, and use that type instead.

type
  TDSOArray = array[0..31] of double;

 function RetrieveDSOData(whatchannels: uchar; 
  var DSOCH1, DSOCH2: TDSOArray;
  var LADATA: array of ushort; 
  Nth_Sample: uchar): longint; stdcall; external 'E_l80.dll';

This will at least resolve the compiler errors. I'm a little confused by how you got from an array of points from the DSO channels to array[0..31] of double. I can't answer the rest of your question either, for the same reason - I don't know what LA Data is, so I don't know how you got to array of ushort for the LADATA parameter.

edited May 16, 2015 at 2:29

answered May 16, 2015 at 0:13

Ken White

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16 Comments

Jerry Dodge Over a year ago

On a side note, from what I've understood, the difference between "declare" and "define" is "define" is how you create a type, whereas "declare" is how you use that type as a variable. Is that correct?

Ken White Over a year ago

@Jerry: Thanks. Corrected. (Define seems more correct from a vocabulary standpoint. It is defining a type, not declaring you have one.)

Ken White Over a year ago

@JustMarc: I've edited my answer; I can't interpret the types you provided later in the question, because you didn't include the information needed to do so, and I've no knowledge regarding the DLL you're trying to use. I've added specifics in my answer.

Ken White Over a year ago

@JustMarc; What you posted here (which you said was with explanations like this) isn't clear. Somewhere there has to be information about what "LADATA: A pointer to an array of LA data" means; I don't know what LA is, so I don't know what *an array of LA data might be.

David Heffernan Over a year ago

Almost certainly the arrays should be translated as pointers. And the open array var LADATA: array of ushort; can't match unsigned short *LADATA which is a plain by value PWord.

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