problem with delphi function which returns array of byte

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2 total messages Started by Rolf Fankhauser Thu, 03 Feb 2005 09:01

#72

Author: Rolf Fankhauser
Date: Thu, 03 Feb 2005 09:01

38 lines
2282 bytes

I have problems to use some functions in CBuilder which I wrote in Delphi:

function ConvertCodeToKey(Code: string): TKey;
function CheckRegistration(Name: string; Key: TKey) : boolean;
function ConvertNameToKey(Name: string): TKey;
function ConvertKeyToCode(Key: TKey): string;

TKey is defined as follows:

type
         TKey = array [0..15] of Byte;

These functions are converted by CBuilder to:

extern PACKAGE Byte __fastcall ConvertCodeToKey(AnsiString Code);
extern PACKAGE bool __fastcall CheckRegistration(AnsiString Name, const 
Byte * Key);
extern PACKAGE Byte __fastcall ConvertNameToKey(AnsiString Name);
PACKAGE AnsiString __fastcall ConvertKeyToCode(const Byte * Key);

My problem is how to access the array of bytes in CBuilder. It returns 
only one byte and not the whole array. Or is this the pointer to the array?
I tried it by the following code but CheckRegistration is always false 
even with a matching pair of user name and key:

bool Regd = false;
AnsiString RegKey = "2LTNRVJRYSN:][aM";
Byte Key = ConvertCodeToKey(RegKey);
ShowMessage(IntToStr(Key));
if (!CheckRegistration("Rolf Fankhauser",&Key))
  Regd = FormRegistration->InputRegistration("REBEKA","TestReg.ini",15);

if (Regd)
  ShowMessage("Registered!");
else
  ShowMessage("Not registered!");

Any idea how to get the whole array of byte?

Re: problem with delphi function which returns array of byte

#73

Author: Alisdair Meredith [TeamB]
Date: Thu, 03 Feb 2005 09:14

28 lines
1897 bytes

Rolf Fankhauser wrote:

> My problem is how to access the array of bytes in CBuilder. It
> returns only one byte and not the whole array. Or is this the pointer
> to the array?

Correct, that is how arrays work in C, and so in C++.
In C you would normally pass an extra integer to know how long the
array is.  Obviously that is not necessary for Delphi where the array
type contains more information and is bounds-checked at runtime.

So yes, assume the rest of the array is there and you can access the
elements with the syntax  :
  Key[3] = 5;

and so on.

But now you have 2 choices to make:

i/ Accept the fact you know the array size is fixed, but not
communicated to the software.  Run the risk of the Delphi definition
changing and maybe breaking your program.

ii/ Add an extra integer parameter to the function calls that is
redundant and useless in Delphi, to tell C++ code the size of the array.

AlisdairM(TeamB)

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