Question

I used same function ( OneWayEncrypt(edit1.Text) ) in Delphi 5 and 2010.
Why the results are different? (Or how can I give the same results from Delphi 2010?)

uses Sysutils, Windows, Dialogs, classes;

function OneWayEncrypt(AStr: string): string;
PROCEDURE CalcCRC32 (p:  pointer; ByteCount:  DWORD; VAR CRCvalue:  DWORD);

implementation

const 
  table:  ARRAY[0..255] OF DWORD = 
  (
    //table consts are here
  );

PROCEDURE CalcCRC32(p: pointer; ByteCount: DWORD; VAR CRCvalue: DWORD);
VAR
  i: DWORD;
  q: ^Byte;
BEGIN
  q := p;
  FOR i := 0 TO ByteCount - 1 DO
  BEGIN
    CRCvalue := (CRCvalue SHR 8) XOR table[q^ XOR (CRCvalue AND $000000FF)];
    INC(q);
  END
END;

function OneWayEncrypt(AStr: string): string;
var
  dwCrc: DWORD;
  s: string;
begin
  dwCrc := $FFFFFFFF; 
  s := 'X' + AStr + '7F';
  CalcCRC32(Addr(s[1]), Length(s), dwCrc);
  result := IntToHex(dwCrc, 8);
end;

Answer 1

Are you aware that string refers to a Unicode string in D2010, while it refers to AnsiString in versions < D2009? That should be the source of your problem.

So you have two choices:

• You could replace all appearances of string with AnsiString. This should give you the same results as in D5, of course without Unicode support
• You could refactor your code. I guess that the pointer-“hacking” is the crucial part here. But I have to admit, I didn’t take the time to fully understand the code 😉
  (It could very well be that your code can’t be used with Unicode anyways, due to the 255 consts = ISO8859?)