Question

我想进入WinAPI。我从VS中的基本Win32应用程序模板开始。我创建了一个自定义对话框IDD_DIALOG1，并希望替换模板附带的标准对话框。但是，每当我启动应用程序时，它几乎会立即终止。我的对话框不会显示，因为CreateWindowW()失败，GetLastError()返回1407（ERROR_CANNOT_FIND_WND_CLASS）。我不知道问题是什么，因为如果我用任何其他资源（例如自动生成的约束IDD_ABOUTBOX）替换自定义对话框，它也会按预期启动，打开一个窗口。我发现类似的线程有同样的问题，但没有一个解决方案似乎对我有帮助，我不知道下一步该做什么。

main.cpp中：

#include "stdafx.h"
#include "Win32Project1.h"

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;                                // current instance
WCHAR szTitle[MAX_LOADSTRING];                  // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING];            // the main window class name

// Forward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
    _In_opt_ HINSTANCE hPrevInstance,
    _In_ LPWSTR    lpCmdLine,
    _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // Initialize global strings
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDD_DIALOG1, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // Perform application initialization:
    if (!InitInstance(hInstance, nCmdShow))
    {
        return GetLastError();
    }

    MSG msg;

    // Main message loop:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        DispatchMessage(&msg);
    }
    return (int)msg.wParam;
}

ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex = {};
    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WIN32PROJECT1));
    wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    hInst = hInstance;

    HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);
    if (!hWnd)
    {
        return false;
    }

    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    return true;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message) {
        case WM_DESTROY: {
            PostQuitMessage(0);
            break;
        }

        case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            EndPaint(hWnd, &ps);
        }
        break;
    }
    return DefWindowProc(hWnd, message, wParam, lParam);
}

RESOURCE.RC：

// Microsoft Visual C++ generated resource script.
//
#include "resource.h"

#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#ifndef APSTUDIO_INVOKED
#include "targetver.h"
#endif
#define APSTUDIO_HIDDEN_SYMBOLS
#include "windows.h"
#undef APSTUDIO_HIDDEN_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
// English (United States) resources

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US

/////////////////////////////////////////////////////////////////////////////
//
// Icon
//

// Icon with lowest ID value placed first to ensure application icon
// remains consistent on all systems.
IDI_WIN32PROJECT1       ICON                    "Win32Project1.ico"

IDI_SMALL               ICON                    "small.ico"


/////////////////////////////////////////////////////////////////////////////
//
// Menu
//

IDC_WIN32PROJECT1 MENU
BEGIN
    POPUP "&File"
    BEGIN
        MENUITEM "E&xit",                       IDM_EXIT
    END
    POPUP "&Help"
    BEGIN
        MENUITEM "&About ...",                  IDM_ABOUT
    END
END

/////////////////////////////////////////////////////////////////////////////
//
// Dialog
//

IDD_ABOUTBOX DIALOGEX 0, 0, 170, 62
STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENU
CAPTION "About Win32Project1"
FONT 8, "MS Shell Dlg", 0, 0, 0x1
BEGIN
    ICON            IDR_MAINFRAME,IDC_STATIC,14,14,21,20
    LTEXT           "Win32Project1, Version 1.0",IDC_STATIC,42,14,114,8,SS_NOPREFIX
    LTEXT           "Copyright (C) 2017",IDC_STATIC,42,26,114,8
    DEFPUSHBUTTON   "OK",IDOK,113,41,50,14,WS_GROUP
END

IDD_DIALOG1 DIALOGEX 0, 0, 309, 176
STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENU
CAPTION "About Win32Project1"
FONT 8, "MS Shell Dlg", 0, 0, 0x1
BEGIN
    ICON            IDR_MAINFRAME,IDC_STATIC,14,14,21,20
    LTEXT           "Win32Project1, Version 1.0",IDC_STATIC,42,14,114,8,SS_NOPREFIX
    LTEXT           "Copyright (C) 2017",IDC_STATIC,42,26,114,8
    DEFPUSHBUTTON   "OK",IDOK,113,41,50,14,WS_GROUP
END


/////////////////////////////////////////////////////////////////////////////
//
// DESIGNINFO
//

#ifdef APSTUDIO_INVOKED
GUIDELINES DESIGNINFO
BEGIN
    IDD_ABOUTBOX, DIALOG
    BEGIN
        LEFTMARGIN, 7
        RIGHTMARGIN, 163
        TOPMARGIN, 7
        BOTTOMMARGIN, 55
    END

    IDD_DIALOG1, DIALOG
    BEGIN
        LEFTMARGIN, 7
        RIGHTMARGIN, 163
        TOPMARGIN, 7
        BOTTOMMARGIN, 55
    END
END
#endif    // APSTUDIO_INVOKED


#ifdef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// TEXTINCLUDE
//

1 TEXTINCLUDE 
BEGIN
    "resource.h\0"
END

2 TEXTINCLUDE 
BEGIN
    "#ifndef APSTUDIO_INVOKED\r\n"
    "#include ""targetver.h""\r\n"
    "#endif\r\n"
    "#define APSTUDIO_HIDDEN_SYMBOLS\r\n"
    "#include ""windows.h""\r\n"
    "#undef APSTUDIO_HIDDEN_SYMBOLS\r\n"
    "\0"
END

3 TEXTINCLUDE 
BEGIN
    "\r\n"
    "\0"
END

#endif    // APSTUDIO_INVOKED


/////////////////////////////////////////////////////////////////////////////
//
// String Table
//

STRINGTABLE
BEGIN
    IDS_APP_TITLE           "Win32Project1"
    IDC_WIN32PROJECT1       "WIN32PROJECT1"
END

#endif    // English (United States) resources
/////////////////////////////////////////////////////////////////////////////



#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 3 resource.
//


/////////////////////////////////////////////////////////////////////////////
#endif    // not APSTUDIO_INVOKED

Answer 1

ERROR_CANNOT_FIND_WND_CLASS means that Windows cannot use the class, most likely because the class does not exist. You never check the return value of MyRegisterClass!

It is rare to use LoadString to get the class name, most people just put the class name string directly in the code. You never check if LoadString was successful and you cannot load a dialog (IDD_DIALOG1) with LoadString!

You could probably just replace WCHAR szWindowClass[MAX_LOADSTRING]; with const WCHAR* L"MyClass"; and it should work. If you still want to load the class name from the resources then you must make sure you are actually loading a valid string.

Win32 API无法创建CreateWindowW（）

1 个答案: