AS. 自结束相关问题以来——下文中增加了更多例子。

下面的简单法典(它找到了顶级Ie窗口,并列举了其儿童)是行之有效的。 配有32个视窗目标平台。 以前版本的德尔菲也没有问题:

procedure TForm1.Button1Click(Sender: TObject);

  function EnumChildren(hwnd: HWND; lParam: LPARAM): BOOL; stdcall;
  const
    Server =  Internet Explorer_Server ;
  var
    ClassName: array[0..24] of Char;
  begin
    Assert(IsWindow(hwnd));            // <- Assertion fails with 64-bit
    GetClassName(hwnd, ClassName, Length(ClassName));
    Result := ClassName <> Server;
    if not Result then
      PUINT_PTR(lParam)^ := hwnd;
  end;

var
  Wnd, WndChild: HWND;
begin
  Wnd := FindWindow( IEFrame , nil); // top level IE
  if Wnd <> 0 then begin
    WndChild := 0;
    EnumChildWindows(Wnd, @EnumChildren, UINT_PTR(@WndChild));

    if WndChild <> 0 then
      ..    

end;

I ve 插入Asert,以表明其没有64-bitWindows目标平台。 如果Iun-nest,则该守则没有任何问题。 背书。

我不敢肯定,这些错误的数值是否与参数一致,是否只是垃圾,或者是由于某些错误的记忆地址(回顾公约?)造成的。 nes击是不是我首先应该做的事情吗? 或者,这只是我不得不面对的一个缺陷?

edit:
In response to David s answer, the same code having EnumChildWindows declared with a typed callback. Works fine with 32-bit:

(edit: The below does not really test what David says since I still used the @ operator. It works fine with the operator, but if I remove it, it indeed does not compile unless I un-nest the callback)

type
  TFNEnumChild = function(hwnd: HWND; lParam: LPARAM): Bool; stdcall;

function TypedEnumChildWindows(hWndParent: HWND; lpEnumFunc: TFNEnumChild;
    lParam: LPARAM): BOOL; stdcall; external user32 name  EnumChildWindows ;

procedure TForm1.Button1Click(Sender: TObject);

  function EnumChildren(hwnd: HWND; lParam: LPARAM): BOOL; stdcall;
  const
    Server =  Internet Explorer_Server ;
  var
    ClassName: array[0..24] of Char;
  begin
    Assert(IsWindow(hwnd));            // <- Assertion fails with 64-bit
    GetClassName(hwnd, ClassName, Length(ClassName));
    Result := ClassName <> Server;
    if not Result then
      PUINT_PTR(lParam)^ := hwnd;
  end;

var
  Wnd, WndChild: HWND;
begin
  Wnd := FindWindow( IEFrame , nil); // top level IE
  if Wnd <> 0 then begin
    WndChild := 0;
    TypedEnumChildWindows(Wnd, @EnumChildren, UINT_PTR(@WndChild));

    if WndChild <> 0 then
      ..

end;

Actually this limitation is not specific to a Windows API callbacks, but the same problem happens when taking address of that function into a variable of procedural type and passing it, for example, as a custom comparator to TList.Sort.

http://docwiki.embarcadero.com/RADStudio/Rio/en/Procedural_Types

procedure TForm2.btn1Click(Sender: TObject);
var s : TStringList;

  function compare(s : TStringList; i1, i2 : integer) : integer;
  begin
    result := CompareText(s[i1], s[i2]);
  end;

begin
  s := TStringList.Create;
  try
    s.add( s1 );
    s.add( s2 );
    s.add( s3 );
    s.CustomSort(@compare);
  finally
    s.free;
  end;
end;

在为Win64汇编成册时,它按预期运作,但未能使用<条码>。 <代码>compare,s = nil 和i2 = 某些随机值;

如果在<代码>btn1Click功能之外有一 extractcompare功能,则即便是Win64目标,也按预期运作。