大家帮我看看这段代码，哪儿错了

[hamzsy]

运行后显示'CreateWindow failed'，请帮忙看看原因。

unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

TMyData=record
lpszInfo:PChar;
dwNumber:DWORD;
end;

PMyData=^TMyData;

var
Form1: TForm1;

implementation

{$R *.dfm}

function WindowProc(TheWindow:HWnd;TheMessage,WParam,
LParam:Longint):Longint;stdcall;
var
lpszInfoString:PChar;
dwInfoNumber:DWORD;
begin
case TheMessage of
WM_CREATE:
begin
lpszInfoString:=PMyData(PCreateStruct(LParam).lpCreateParams).lpszInfo;
dwInfoNumber:=PMyData(PCreateStruct(LParam).lpCreateParams).dwNumber;
ShowMessage(Format('String:%s'+Chr(13)+'Number:%d',
[lpszInfoString,dwInfoNumber]));
end;
WM_DESTROY:
begin
PostQuitMessage(0);
Exit;
end;
end;
end;

function RegisterClass:Boolean;
var
WindowClass:TWndClass;
begin
WindowClass.style:=CS_HREDRAW or CS_VREDRAW;
WindowClass.lpfnWndProc:=@WindowProc;
WindowClass.cbClsExtra:=0;
WindowClass.cbWndExtra:=0;
WindowClass.hInstance:=hInstance;
WindowClass.hIcon:=LoadIcon(0,IDI_WINLOGO);
WindowClass.hCursor:=LoadCursor(0,IDC_APPSTARTING);
WindowClass.hbrBackground:=COLOR_WINDOW;
WindowClass.lpszClassName:='TestClass';
Result:=Windows.RegisterClass(WindowClass)<>0;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
hWindow:HWND;
ExtraCreationData:TMyData;
begin
if not RegisterClass then
begin
ShowMessage('RegisterClass failed');
Exit;
end;

ExtraCreationData.lpszInfo:='ExtraCreationData information string';
ExtraCreationData.dwNumber:=12345;

hWindow:=CreateWindow('TestClass',
'API Window',
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
Form1.Handle,
0,
hInstance,
@ExtraCreationData
);
if hWindow<>0 then
begin
ShowWindow(hWindow,SW_SHOWNORMAL);
UpdateWindow(hWindow);
end
else
begin
ShowMessage('CreateWindow failed');
Exit;
end;
end;

end.

[Wnyu]

var
WindowClass:TWndClass;
begin
FillChar(WindowClass,sizeof(TWndClass),0); // Add this!
WindowClass.style:=CS_HREDRAW or CS_VREDRAW;
.....
......

[netxeyes]

var
windowclass : WNDCLASS;

[hamzsy]

试试先

[hamzsy]

还不行啊，各位

[dext]

如果你把这段代码修改一下放在一个单独的工程文件中（只有一个工程文件）
应该可以运行。
我认为问题就出在，你又用了VCL,又用了API.

[hamzsy]

这也会有冲突？

[halfdream]

是你的WindowProc函数写的问题。

你在其中应该加上一个缺省处理，
case theMessage of
....
else Result:=DefWindowProc(theWindow,theMessage,WParam,LParam);
end;

[hamzsy]

再看看

[hamzsy]

感谢halfdream(哈欠)，上面的代码已调试通过
但下面的代码运行后窗体只是闪了一下，如何修改才能保持住？

program Project1;

uses
Windows,
Messages,
SysUtils,
Variants,
Classes,
Dialogs;

{$R *.res}
type
TMyData=record
lpszInfo:PChar;
dwNumber:DWORD;
end;

PMyData=^TMyData;

function WindowProc(TheWindow:HWnd;TheMessage,WParam,
LParam:Longint):Longint;stdcall;
var
lpszInfoString:PChar;
dwInfoNumber:DWORD;
begin
case TheMessage of
WM_CREATE:
begin
lpszInfoString:=PMyData(PCreateStruct(LParam).lpCreateParams).lpszInfo;
dwInfoNumber:=PMyData(PCreateStruct(LParam).lpCreateParams).dwNumber;
// ShowMessage(Format('String:%s'+Chr(13)+'Number:%d',
// [lpszInfoString,dwInfoNumber]));
end;
WM_DESTROY:
begin
PostQuitMessage(0);
Exit;
end
else Result:=DefWindowProc(theWindow,theMessage,WParam,LParam);
end;
end;

function RegisterClass:Boolean;
var
WindowClass:TWndClass;
begin
WindowClass.style:=CS_HREDRAW or CS_VREDRAW;
WindowClass.lpfnWndProc:=@WindowProc;
WindowClass.cbClsExtra:=0;
WindowClass.cbWndExtra:=0;
WindowClass.hInstance:=hInstance;
WindowClass.hIcon:=LoadIcon(0,IDI_WINLOGO);
WindowClass.hCursor:=LoadCursor(0,IDC_APPSTARTING);
//WindowClass.hCursor:=LoadCursor(0,IDC_ARROW);
WindowClass.hbrBackground:=COLOR_WINDOW;
WindowClass.lpszClassName:='TestClass';
Result:=Windows.RegisterClass(WindowClass)<>0;
end;

var
hWindow:HWND;
ExtraCreationData:TMyData;
begin
if not RegisterClass then
begin
ShowMessage('RegisterClass failed');
Exit;
end;

ExtraCreationData.lpszInfo:='ExtraCreationData information string';
ExtraCreationData.dwNumber:=12345;

hWindow:=CreateWindow('TestClass',
'API Window',
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
0,
0,
hInstance,
@ExtraCreationData
);
if hWindow<>0 then
begin
ShowWindow(hWindow,SW_SHOWNORMAL);
UpdateWindow(hWindow);
end
else
begin
ShowMessage('CreateWindow failed');
Exit;
end;

end.

[xzgyb]

加一消息循环
声明
uMsg: TMsg;

if hWindow<>0 then
begin
ShowWindow(hWindow,SW_SHOWNORMAL);
UpdateWindow(hWindow);
while not GetMessage(uMsg, 0, 0, 0) do
begin
TranslateMessage(uMsg);
DispatchMessage(uMsg);
end;
end

[hamzsy]

这段代码是CORE API上的，没想到代码这么多缺陷
试试先

[hamzsy]

楼上的应该是
begin
ShowWindow(hWindow,SW_SHOWNORMAL);
UpdateWindow(hWindow);
while GetMessage(uMsg, 0, 0, 0) do
begin
TranslateMessage(uMsg);
DispatchMessage(uMsg);
end;
end

[hamzsy]

第一次认真搞了一下API，问题已一一解决了，多谢各位帮忙，少走了许多弯路。