Delphi writes and calls the DLL (DELPHI7 test pass)

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1 Delphi Writing DLLs2The following is a simple DLL written in Delphi, where there is only one Max function, which returns a large number of 2 numbers (Delphi5.0)3 1, new->dll; named Dll_0001, write the code:4 LibraryDll_0001;5 uses6 Sysutils,7 Classes;8 {$R *. RES}9 functionMax (X,y:integer): integer;stdcall;Ten begin One      if(x>y) Then AMax: =x -       Else -Max: =y; the End; - exportsMax; - begin - End. + The red part is written for itself, this is the same as the normal Delphi function, just take a stdcall parameter in the return value, and then use exports to export the function -================================================================================ + DELPHL calling DLLs A Call DLL in dynamic call and static call 2, dynamic call write simple, secure point, dynamic call complex many, but very flexible; atNow write a program to invoke the Dll_ written above0001the Max function in a. dll file -First, new A application, put 2 tedit in the form,1a Tlabek; - Second, - 1, static invocation - UnitUnit1; - Interface in uses - Windows, Messages, Sysutils, Classes, Graphics, Controls, Forms, Dialogs, to Stdctrls; + type -TForm1 =class(Tform) the Edit1:tedit; * Edit2:tedit; $ Label1:tlabel;Panax Notoginseng      procedureEdit2keydown (Sender:tobject;varKey:word; - shift:tshiftstate); the    Private +      {Private Declarations} A     Public the      {Public Declarations} +    End; - var $ Form1:tform1; $ Implementation - {$R *. DFM} - functionMax (X,y:integer): integer;stdcall; the External 'Dll_0001.dll'; - procedureTform1.edit2keydown (Sender:tobject;varKey:word;Wuyi shift:tshiftstate); the begin - ifKey =vk_return Then WuLabel1. Caption: =IntToStr (Max (Strtoint (Edit1.text), Strtoint (Edit2.text))); - End; About End. $ The Red code adds itself, where the dll_name in external "dll_name" can be the absolute path to the DLL, and if the DLL file is in your search path, you can write the file name directly, but the. dll cannot write less - 2, dynamic invocation, code as follows; - UnitUnit1; - Interface A uses + Windows, Messages, Sysutils, Classes, Graphics, Controls, Forms, Dialogs, the Stdctrls; - type $TForm1 =class(Tform) the Edit1:tedit; the Edit2:tedit; the Label1:tlabel; the      procedureEdit2keydown (Sender:tobject;varKey:word; - shift:tshiftstate); in    Private the      {Private Declarations} the     Public About      {Public Declarations} the    End; the var the Form1:tform1; + Implementation - {$R *. DFM} the procedureTform1.edit2keydown (Sender:tobject;varKey:word;Bayi shift:tshiftstate); the type theTfunc =function(x,y:integer): integer;stdcall; - var - Th:thandle; the Tf:tfunc; the Tp:tfarproc; the begin the ifKey =vk_return Then - begin theTh: =loadlibrary ('Dll_0001.dll');{Load DLL} the if(Th >0) Then the Try94Tp: =getprocaddress (Th,pchar ('Max')); the if(Tp <>Nil) Then the begin         {begin 1} theTf: =Tfunc (Tp);98Label1.Caption: =IntToStr ( About Tf (Strtoint (Edit1.text), Strtoint (Edit2.text))); - End   {End 1}101 Else102ShowMessage ('function Max not found.');103 finally104 FreeLibrary (Th); the End106 Else107ShowMessage ('Dll_0001.dll not exsit.');108 109 End; the End;111 End.

Delphi writes and calls the DLL (DELPHI7 test pass)