What is the Problem in this code?

Hi All

I am new to delphi coing.

Please check this code. And please explain me where i am doing mistakes

Dll Code:

library sudhakar;


uses
  ShareMem,
  Windows,
  SysUtils,
  Classes,
  Axctrls,
  ActiveX,
  Dialogs,
  ShellApi
;
{$R *.RES}

procedure tester(x:Char;var y:PChar;alloc: longInt);
var
  xx:longint;
  zzz:PChar;
begin
  try
    //GetMem(y,alloc);
    y:='hello';
    showmessage(y);
  except
  end;
end;
exports
 tester;
begin

end.













Application Code:

unit Unit111;

interface

uses
  ShareMem,Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;
procedure tester(x:Char;var y:PChar;alloc: longInt);stdcall;external 'c:\windows\desktop\test\sudhakar.Dll' ;
type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var
xx: PChar;
yy: Char;
begin
try
        yy:='a';
        GetMem(xx,101);
        tester(yy,xx,110);
        showmessage(xx);
except
end;
end;

end.




what is the problem in the above code?

Actually my requirement is i want to manage external PChar Data in dll and i am facing problems and is giving memory access voilation exception.

i tried to allocate the memory for pchar data external to dll and with in dll, but both are giving memory access voilation problems with different results.I am not understanding whare i am doing mistake.




Thanks in advance
Sudhakar Koundinya