The data is read only for the DLL developer, so perhaps this will work fine then. Is the way I've written the C++ struct correct to give to a plugin developer?
Thanks, Ross. ----- Original Message ----- From: "Jason Nelson" <[EMAIL PROTECTED]> To: "Borland's Delphi Discussion List" <[email protected]> Sent: Friday, February 09, 2007 3:16 AM Subject: Re: C++ DLL accessing Delphi strings Ok, well what you're doing there MIGHT almost work provided that the strings are READ ONLY. But since you want to change the strings, you're going to have issues with a couple of things: I'm not warranting that my knowledge here is totally right.... but I think some of these points are worth double-checking. 1. Pascal strings maintain a reference count which is made thread-safe via bus locks (disassemble some string processing to see the ASM code). 2. Pointers to pascal strings (i think) point to the beginning of the string data to be compatible with pchars with the auxiliary data to the LEFT of the pointer. So if you're going to send them delphistring structs, you might need to do a bit of pointer subtraction. I could be wrong on this though. Jason There are some other string OLE types that are more suited for this type of thing. ----- Original Message ----- From: "Ross Levis" <[EMAIL PROTECTED]> To: "Delphi Discussion List" <[email protected]> Sent: Tuesday, February 06, 2007 9:33 PM Subject: C++ DLL accessing Delphi strings > I've adding a plugin DLL interface to my Delphi app so 3rd party DLL's > can > utilize functions in my app. I'm not going to change pascal strings > into > pChars just to suit C++ developers so I need to write the > documentation > describing a record structure containing strings for a C++ developer. > > I know very little about the C language. Can someone confirm if I > have > this right please. > > MyRecord = packed record > Artist: String; > Title: String; > Duration: Integer; > Year: Word; > Gender: ShortInt; > BPM: Byte; > Cuedb: SmallInt; > Cue: LongWord; > end; > > typedef struct { > int StringLen; > char String; > } delphistring; > > typedef struct{ > delphistring *Artist; > delphistring *Title; > int Duration; > unsigned short Year; > signed char Gender; > unsigned char Byte; > short Cuedb; > unsigned long Cue; > } MyRecord; > > Many thanks, > Ross. _______________________________________________ Delphi mailing list -> [email protected] http://www.elists.org/mailman/listinfo/delphi
