Question

Since I’ve upgraded from delphi 5 to XE I’m struggling to use specific Dlls that were compiled a while ago. My blocking point seems related to the unicode/ansi character but I haven’t found out how to solve the problem

Here is an example of procedure:

procedure GetFilename(Buffer: PChar; BufSize: Integer); stdcall;

In my code I’m calling this that way

implementation    
procedure GetFilename; external 'myDll.dll' name 'GetFilename';
procedure myproc
var
  buffer : Array [0..255] of Char;
begin
  GetFilename(buffer, length(buffer)-1);
  Showmessage(buffer); //This gives me chinese character
end; 

Buffer contains this:

byte((@buffer[0])^); // 67 which is the ASCII for C
byte((@buffer[1])^); // 92 which is the ASCII for \

what I’m expecting normal is a string starting with “C:\”

Has anyone faced the same problem?

Answer 1

Because the dll was made using a non-Unicode version of Delphi you must change the declaration from

procedure GetFilename(Buffer: PChar; BufSize: Integer); stdcall;

to

procedure GetFilename(Buffer: PAnsiChar; BufSize: Integer); stdcall;

and the buffer variable from

buffer : Array [0..255] of Char;

to

buffer : Array [0..255] of AnsiChar;

Additionally to learn about the Delphi Unicode support take a look to the Delphi and Unicode Whitepaper from Marco Cantú.