專案Project1.exe引發例外類ERangeError并顯示訊息“范圍檢查錯誤”

我正在閱讀一本關于 Windows API 的舊 Delphi 書。這是其中的一個例子。

unit Unit1;

interface

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
    System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

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

var
    Form1: TForm1;

implementation

{$R *.dfm}

{ Register the Window Class }
function RegisterClass: Boolean;
var
    WindowClass: TWndClass;
begin
    { setup our new window class }
    WindowClass.Style := CS_HREDRAW or CS_VREDRAW; { set the class styles }
    WindowClass.lpfnWndProc := @DefWindowProc;     { point to the default window procedure }
    WindowClass.cbClsExtra := 0;                   { no extra class memory }
    WindowClass.cbWndExtra := 0;                   { no extra window memory }
    WindowClass.hInstance := hInstance;            { the application instance }
    WindowClass.hIcon := 0;                        { no icon specified }
    WindowClass.hCursor := 0;                      { no cursor specified }
    WindowClass.hbrBackground := COLOR_WINDOW;     { use a predefined color }
    WindowClass.lpszMenuName := nil;               { no menu }
    WindowClass.lpszClassName := 'TestClass';      { the registered class name }

    { now that we have our class set up, register it with the system }
    Result := Winapi.Windows.RegisterClass(WindowClass) <> 0;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
    hWindow: HWND;
begin
    { Step 1: Register our new window class }
    if not RegisterClass then
    begin
        ShowMessage('RegisterClass failed');
        Exit;
    end;

    { Step 2: Create a window based on our new class }
    hWindow := CreateWindowEx(0, { no extended styles }
        'TestClass',             { the registered class name }
        'New Window',            { the title bar text }
        WS_OVERLAPPEDWINDOW,     { a normal window style }
        CW_USEDEFAULT,           { default horizontal position }
        CW_USEDEFAULT,           { default vertical position }
        CW_USEDEFAULT,           { default width }
        CW_USEDEFAULT,           { default height }
        0,                       { no owner window }
        0,                       { no menu }
        hInstance,               { the application instance }
        nil                      { no additional information }
        );

    { Step 3: If our window was created successfully, display it }
    if hWindow <> 0 then
    begin
        ShowWindow(hWindow, SW_SHOWNORMAL);
        UpdateWindow(hWindow);
    end
    else
    begin
        ShowMessage('CreateWindow failed');
        Exit;
    end;
end;

end.

用戶界面非常簡單。我只是拖動一個按鈕并將其放在表單上。但是，當我運行程式Embarcadero? Delphi 11.0 Version 28.0.42600.6491并單擊表單上的按鈕時，我收到Project Project1.exe 引發的例外類 ERangeError 并顯示訊息“范圍檢查錯誤”。. 之后，我收到了這個錯誤。

誰能幫忙看看問題出在哪里？

順便說一句，我剛試過 Delphi 7，程式運行正常。當我單擊按鈕時，會彈出一個空視窗。

uj5u.com熱心網友回復：

CW_USEDEFAULT 常量的值與 CreateWindowEx 函式的宣告不太一致。將以下代碼添加到 Button1Click 的頂部，靠近 var 部分：

const
  CW_USEDEFAULT = -MaxInt - 1;

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