动态调用 DLL 中的函数

By definition DLLs are dynamically loaded libraries of functions and sometimesdata. However, it's possible to either hard code the ability to "import"functions from DLLs or dynamically "bind" a DLL during the run time --which of course means that we don't necessarily need to know the name ofthe DLL nor the name of the function we're about to call (to a certain extent)during the time we code. Dynamically loading and unloading DLLs could notonly save memory, but also can help you write programs that are able to"adjust" itself if certain DLLs are missing.Following "LoadAndRunDLLProcedure()"function will let you pass the name of the DLL you want to connect to andthe name of the function you want to call. If everything goes well, it willload the DLL, call the function, and then unload the DLL.

function LoadAndRunDLLProcedure(  sDLL,  sFunc : string )  : boolean;type  // define the type of "function"  // we're calling  TFunc_Start = procedure;var  Func_Start : TFunc_Start;  hDll       : THandle;  FuncPtr    : TFarProc;  sMsg       : string;begin  Result := False;  hDll   := LoadLibrary(              PChar( sDLL ) );  if(hDll > 32)then  begin    FuncPtr :=      GetProcAddress(        hDll, PChar( sFunc ) );    @Func_Start := FuncPtr;    if(nil <> @Func_Start)then    begin      Func_Start;      Result := True;    end else    begin      sMsg := 'DLL entry point ' +              sFunc + ' not found';      MessageBox(        0, PChar( sMsg ), 'Error',        MB_OK );    end;    FreeLibrary( hDll );  end else  begin    sMsg := 'File ' + sDLL +            ' not found';    MessageBox(      0, PChar( sMsg ), 'Error',      MB_OK );  end;end;For example, let's say you want to call a procedure called "HelloWorld()"in a DLL named "MyStuff.DLL:"LoadAndRunDLLProcedure(  'MyStuff.DLL',  'HelloWorld' );Please note that HelloWorld() must be a procedure, for example, declared as:procedure HelloWorld;or in C:void HelloWorld();