用Delphi編寫和調用DLL

用Delphi編寫和調用DLL

建立一個DLL工程先，再在工程中建立一個單元檔案，在該檔案中聲明并實作你的加密與解密方法，在DLL中對字元串操作時，盡量使用PChar 。

//Delphi(Pascal) code

unit Unit1;

interface

function encrypt(Str: PChar): PChar;
function decrypt(Str: PChar): PChar;

implementation

function encrypt(Str: PChar): PChar;
begin
  //your code
end;

function decrypt(Str: PChar): PChar;
begin
  //your code
end;

end.
           

然後在你的DLL工程中輸出這兩個方法

Delphi(Pascal) code

library Project1;

{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  Project-View Source) USES clause if your DLL exports any procedures or
  functions that pass strings as parameters or function results. This
  applies to all strings passed to and from your DLL--even those that
  are nested in records and classes. ShareMem is the interface unit to
  the BORLNDMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using BORLNDMM.DLL, pass string information
  using PChar or ShortString parameters. }

uses
  SysUtils,
  Classes,
  Unit1 in 'Unit1.pas';

{$R *.res}

Exports
   encrypt;
   decrypt;

begin
end.
           

調用代碼如下：

//Delphi(Pascal) code

type
  TMyFun = function (Str: PChar): PChar

procedure TForm1.Test;
var
  s: String;
  P: PChar;
  MyFun: TMyFun;
  LibHandle: THandle;
begin
  s := 'abcdefg';
  LibHandle := LoadLibrary(DLLFileName);//你編譯後的DLL所在的路徑
  try
    if LibHandle =  then begin  
      MyFun := GetProcAddress(LibHandle, 'encrypt');
      if Assigned(MyFun) then
        MyFun(PChar(s));
  finally
    FreeLibrary(LibHandle);
  end;
end;
           

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