DLL programmieren

[Christian18]

Hallo,

ich beschäftige mich gerade mit DLLs. Da ich die Verwendung der ShareMem Unit vermeiden will, übergebe ich die Strings als PChar.

Meine Fragen sind nun:

1. Kann man in den Funktionen trotzdem Strings verwenden? Oder zum Beispiel String Funktionen. IntToStr, ReverseString, ...

2. DecToX und XToDec sollen von einer anderen Software nicht aufgerufen werden können. Reicht es diese nicht in den Exports zu schreiben?

MFG Christian18

Delphi-Quellcode:

library DLLNumberSystems;

uses
  SysUtils, Classes, StrUtils, Math;

{$R *.res}

function DecToX(Value: Byte; Basis: Byte) : PChar;
begin
  Result:='';
  while Value > 0 do
    begin
      case Value mod Basis of
        10 : Result:=PChar(Result + 'A');
        11 : Result:=PChar(Result + 'B');
        12 : Result:=PChar(Result + 'C');
        13 : Result:=PChar(Result + 'D');
        14 : Result:=PChar(Result + 'E');
        15 : Result:=PChar(Result + 'F');
        else Result:=PChar(Result + IntToStr(Value mod Basis));
      end;
      Value:=Value div Basis;
    end;
  Result:=PChar(ReverseString(Result));
end;

function XToDec(Value: PChar; Basis: Byte) : Byte;
  var i : Integer;  // Schleifenvariable
begin
  Result:=0;
  Value:=PChar(ReverseString(Value));
  for i:=1 to Length(Value) do
    begin
      case Value[i] of
        'A' : Result:=Result + Round((10 * Power(Basis, i - 1)));
        'B' : Result:=Result + Round((11 * Power(Basis, i - 1)));
        'C' : Result:=Result + Round((12 * Power(Basis, i - 1)));
        'D' : Result:=Result + Round((13 * Power(Basis, i - 1)));
        'E' : Result:=Result + Round((14 * Power(Basis, i - 1)));
        'F' : Result:=Result + Round((15 * Power(Basis, i - 1)));
        else Result:=Result + Round((StrToInt(Value[i]) * Power(Basis, i - 1)));
      end;
    end;
end;

function HexToDec(Value: PChar) : PChar;
begin
  Result:=PChar(IntToStr(XToDec(Value, 16)));
end;

function HexToOct(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(XToDec(Value, 16), 8));
end;

function HexToBin(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(XToDec(Value, 16), 2));
end;

function DecToHex(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(StrToInt(Value), 16));
end;

function DecToOct(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(StrToInt(Value), 8));
end;

function DecToBin(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(StrToInt(Value), 2));
end;

function OctToHex(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(XToDec(Value, 8), 16));
end;

function OctToDec(Value: PChar) : PChar;
begin
  Result:=PChar(IntToStr(XToDec(Value, 8)));
end;

function OctToBin(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(XToDec(Value, 8), 2));
end;

function BinToHex(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(XToDec(Value, 2), 16));
end;

function BinToDec(Value: PChar) : PChar;
begin
  Result:=PChar(IntToStr(XToDec(Value, 2)));
end;

function BinToOct(Value: PChar) : PChar;
begin
  Result:=PChar(DecToX(XToDec(Value, 2), 8));
end;

exports
  HexToDec, HexToOct, HexToBin,
  DecToHex, DecToOct, DecToBin,
  OctToHex, OctToDec, OctToBin,
  BinToHex, BinToDec, BinToOct;

begin

end.