C++ WIN API：为什么我不能使用 WM_CREATE [关闭]

Question

我正在尝试学习 Winapi 以在 C++ 中开发 gui，但我在使用 VM_CREATE 时遇到了问题我的代码直到 VM_CREATE 工作正常，但代码以防 VM_CREATE 不起作用我使用的是 Visual Studio 2017 这是我的代码::: (Visual工作室没有给出错误）什么问题

#include <windows.h>
#include <tchar.h>  



LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

HWND textfield, hwnd, Button;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {

    WNDCLASSEX wc;
    MSG msg;
    memset(&wc, 0, sizeof(wc));
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszClassName = L"WindowClass";
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

    if (!RegisterClassEx(&wc)) {
        MessageBox(NULL, L"Window Registration Failed!", L"Error!", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, L"WindowClass", L"Window", WS_VISIBLE | WS_MINIMIZEBOX | WS_SYSMENU,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        500,
        500,
        NULL, NULL, hInstance, NULL);

    while (GetMessage(&msg, NULL, 0, 0) > 0) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}


LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{

    switch (message)
    {

    case WM_CREATE:                     // WORKS TILL HERE
    textfield = CreateWindow(L"STATIC", L"HELLO",
            WS_VISIBLE | WS_CHILD | WS_BORDER,
            300, 300, 100, 25,
            hwnd, NULL, NULL, NULL);
    Button = CreateWindow(L"BUTTON",L"Hello this is a button",
                WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,
                20,
                20,
                300,
                300,
                hwnd,
                NULL,
                NULL,
                NULL);

    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }

    return 0;
}

Answer 1

您应该在静态和按钮 CreateWindow 调用的回调中使用 hWnd 输入，而不是在 WM_CREATE 时尚未设置的全局 hwnd被调用（WM_CREATE 在 CreateWindow 返回之前被调用）

所以对于 switch 语句的 WM_CREATE 部分：

textfield = CreateWindow(L"STATIC", L"HELLO",
        WS_VISIBLE | WS_CHILD | WS_BORDER,
        300, 300, 100, 25,
        hWnd, NULL, NULL, NULL);
Button = CreateWindow(L"BUTTON",L"Hello this is a button",
            WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,
            20,
            20,
            300,
            300,
            hWnd,
            NULL,
            NULL,
            NULL);

Answer 2

添加更多参数：

textfield = CreateWindow(L"STATIC", L"HELLO",
                         WS_VISIBLE | WS_CHILD | WS_BORDER,
                         300, 300, 100, 25,
                         hWnd, (HMENU)1, hInstance, NULL);

至少hInstance 很重要。