调用动态链接库的问题？？急用？？

Question

我写了一个动态连接库，里面只有一个函数，现在我想在一个程序中调用他，我在
implentcation 中加入了   function Instr(SourceStr : PChar;Check : Char): Integer; far;
  external 'D:\public\程序\Myth.dll';
可是不行，提示，找不到接口什么的？？这是怎么回事呀？？
哪位大侠能够告诉我动态库到底怎么用呀？？多谢？？？

Answer 1

是不是在Myth.dll里忘了导出函数了，用dependence或者quickview看看

Answer 2

主程序：
//--------------------------------------------------------------------------
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;type
  TShowForm = procedure(AHandle: THandle); stdcall;  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.DFM}procedure TForm1.Button1Click(Sender: TObject);
var
  DLLHandle: THandle;
  ShowForm: TShowForm;
begin
  DLLHandle := LoadLibrary('DLLFile.dll');
  try
    if DLLHandle = 0 then
      raise Exception.Create('Load DLLFile.dll error！');
    @ShowForm := GetProcAddress(DLLHandle, 'ShowForm');
    if @ShowForm = nil then
      Abort;
    ShowForm(Application.Handle);
  finally
    FreeLibrary(DLLHandle);
  end;
end;end.
//--------------------------------------------------------------------------DLL 工程单元
//--------------------------------------------------------------------------
library DLLFile;{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  Project-View Source) USES clause if your DLL exports any procedures or
  functions that pass strings as parameters or function results. This
  applies to all strings passed to and from your DLL--even those that
  are nested in records and classes. ShareMem is the interface unit to
  the BORLNDMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using BORLNDMM.DLL, pass string information
  using PChar or ShortString parameters. }uses
  SysUtils,
  Classes,
  Unit1 in 'Unit1.pas' {DllForm};{$R *.RES}exports
  ShowForm;begin
end.
//--------------------------------------------------------------------------
DLL Form单元
//--------------------------------------------------------------------------
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;type
  TDllForm = class(TForm)
  private
    { Private declarations }
  public
    { Public declarations }
  end;procedure ShowForm(AHandle: THandle); stdcall;implementation{$R *.DFM}procedure ShowForm(AHandle: THandle); stdcall;
var
  DLLForm: TDllForm;
begin
  Application.Handle := AHandle;
  DLLForm := TDLLForm.Create(Application);
  try
    DLLForm.ShowModal;
  finally
    DLLForm.Free;
  end;
end;end.
//

Answer 3

library testdll;uses
  SysUtils,
  Classes,
  DMTEST in 'DMTEST.pas' {CustomerData: TDataModule},
  testunit in 'testunit.pas' {Form2};exports
  showzydlr;
{$R *.RES}begin
end.
-------------------------------------------------------
DLL窗体
unit testunit;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Grids, DBGrids;type
  TForm2 = class(TForm)
    DBGrid1: TDBGrid;
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form2: TForm2;
  procedure showzydlr;stdcall;implementation
uses DMtest;procedure showzydlr;
begin
CustomerData:=TCustomerData.Create(application);
Form2:=TForm2.Create(application);
CustomerData.Orders.Active:=false;
CustomerData.Orders.Active:=true;
Form2.ShowModal;
CustomerData.Free;
Form2.Free;
end;
{$R *.DFM}end.调用
unit zydtest;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;type
  TForm1 = class(TForm)
    Button4: TButton;
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementationprocedure showzydlr;stdcall;external 'testdll.dll'
{$R *.DFM}procedure TForm1.Button4Click(Sender: TObject);
begin
showzydlr;
end;end.