I have a Dll function with this signature:
UInt32 Authenticate(uint8 *Key);
I'm doing this on Delphi:
function Authenticate(Key:string) : UInt32; external 'mylib.dll' name 'Authenticate';
But always, the function return 10 (error code) and the application brakes :\
There is a way to do this right?
UPDATE: thanks guys! you're the best!
There are some problems with your code.
1) uint8
is the equivilent of Byte
in Delphi, not String
.
2) the C code is using the compiler's default calling convention, which is usually __cdecl
. Delphi's default calling convention, on the other hand, is register
instead. They are not compatible with each other. If you mismatch the calling convention, the stack and CPU registers will not be managed correctly during the function call at runtime.
A literal translation of the C code would be this instead:
function Authenticate(Key: PByte) : UInt32; cdecl; external 'mylib.dll';
However, assuming the function is actually expecting a null-terminated string then do this instead:
// the function is expecting a pointer to 8-bit data,
// so DO NOT use `PChar`, which is 16-bit in Delphi 2009+...
function Authenticate(Key: PAnsiChar) : UInt32; cdecl; external 'mylib.dll';
I would stick with the first declaration, as it matches the original C code. Even if the function is expecting a null-terminated string as input, you can still pass it in using PByte
via a type-cast:
var
S: AnsiString;
begin
Authenticate(PByte(PAnsiChar(S)));
end;
Or, if the function allows NULL input for empty strings:
var
S: AnsiString;
begin
Authenticate(PByte(Pointer(S)));
end;
I would add nothing to the great Remy's answer, but I would like to give a list of the tools that can help in conversion of C DLL headers to Pascal (in no special order):
Beware that these converters can only convert 60-80% of the code, so manual work follows.
The biggest time saver tip I can give is to try to find Visual Basic header translation if it exists for your DLL, and use Marco Cantu's VB converter at http://www.marcocantu.com/tools/vb2delphi.htm. This will probably give you almost 100% automatic conversion (if you are converting just DLL headers, of course). There is also a commercial VBTO converter but trial demo is quite enough for conversion of VB DLL headers to Pascal. Download it here: http://www.vbto.net
Other tips for conversion from C--/C++:
Slightly off topic, but I thought this might be useful to someone...
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With