DLL文件动态调用

library AngToArcDLL;   //dll工程的工程名

{ 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;

{$R *.res}

function FunAngToArc(d: double): double; stdcall;   //函数的书写形式
begin
  result := d / 180.0 * pi;
end;

exports                                             //该关键字表明下面将列出需要输出的函数
  FunAngToArc;

begin
end.

 

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

type
  TFunAngToArc = function(d: double): double; stdcall;

procedure TForm1.Button1Click(Sender: TObject);
var
  pfunc: TFarProc;
  hd1: THAndle;
begin
  hd1 := loadlibrary('AngToArcDLL.dll');            //将指定动态链接库装入内存，返回句柄
  if hd1 > 32 then
    begin
      pfunc := GetProcAddress(hd1,'FunAngToArc');   //得到具体函数地址
      edit2.Text := floattostr(TFunAngToArc(pfunc)(strtofloat(edit1.Text)));
    end;
  freelibrary(hd1);                                 //释放动态链接库占用的内存
end;

end.