0x00007FF8956DA430 (user32.dll) 处的未处理异常

Question

I get an error when trying to load my Window Application, the error is called "Unhandled exception at 0x00007FF8956DA430 (user32.dll) in Tennis.exe: 0xC0000005: Access violation reading location"

Windows.cpp -

Windows32::Windows32()
{
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)

{
    switch (msg)
    {
    case WM_CREATE:
    {   Windows32* window = (Windows32*)((LPCREATESTRUCT)lparam)->lpCreateParams;
        SetWindowLongPtr(hwnd, GWLP_USERDATA, (LONG_PTR)window);
        window->onCreate();
        break;
       // case WM_CREATE;
    }

    case WM_DESTROY:
    {   
        Windows32* window = (Windows32*)GetWindowLong(hwnd, GWLP_USERDATA);
        window->onDestroy();
        ::PostQuitMessage(0);
        break;
    }

    default:
        return ::DefWindowProc(hwnd, msg, wparam, lparam);

    }

    return NULL;
}



bool Windows32::init()
{
    WNDCLASSEX wc;
    wc.cbClsExtra = NULL;
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.cbWndExtra = NULL;
    wc.hbrBackground = (HBRUSH)COLOR_WINDOW;;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wc.hInstance = NULL;
    wc.lpszClassName = L"MyWindows32Class";
    wc.lpszClassName = L"";
    wc.style = NULL;
    wc.lpfnWndProc = &WndProc;


    if (!::RegisterClassEx(&wc))
        return false;

   // if (!window)
     //   window = this;


    m_hwnd=::CreateWindowEx(WS_EX_OVERLAPPEDWINDOW, L"MyWindows32Class", L"DirectX Application", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 1024, 768,
        NULL, NULL, NULL, this);


  
    if (!m_hwnd)
        return false;

    ::ShowWindow(m_hwnd, SW_SHOW);
    ::UpdateWindow(m_hwnd);

    //::RegisterClassEx(&wc);
 

  
    
    m_is_run = true;
    return true;
}

bool Windows32::broadcast()
{
    MSG msg;

    this->onUpdate();

    while (::PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) > 0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }


    Sleep(1);
    return true;
}


bool Windows32::release()
{
    if (!::DestroyWindow(m_hwnd))
        return false;
    return true;
}

bool Windows32::isRun()
{
    return m_is_run;
}

void Windows32::onCreate() {

}

void Windows32::onUpdate() {

}
void Windows32::onDestroy()
{
    m_is_run = false;
}

Windows32::~Windows32() {

}

Windows.h

#pragma once
#include <Windows.h>
class Windows32 
{
public:
    Windows32();
    bool init();
    bool broadcast();
    bool release();
    bool isRun();

    virtual void onCreate();
    virtual void onUpdate();
    virtual void onDestroy();




    ~Windows32();
protected:
    HWND m_hwnd;
    bool m_is_run;
};

Main.cpp

#include "Windows32App.h"

int main() {
    Windows32App app;
    if (app.init())
    {
        while (app.isRun())
        {
            app.broadcast();
        }
    }
    
    return 0;
}

WindowsApp.h

#pragma once
#include "Windows32.h"


class Windows32App: public Windows32
{
public:
   Windows32App();
   ~Windows32App();



// Inherited via Windows32
virtual void onCreate() override;
virtual void onUpdate() override;
virtual void onDestroy() override;

};

Windows32App.cpp

#include "Windows32App.h"



Windows32App::Windows32App()
{
}

Windows32App::~Windows32App()
{
}

void Windows32App::onCreate()
{
Windows32::onCreate();
}

void Windows32App::onUpdate()
{
Windows32::onUpdate();
}

void Windows32App::onDestroy()
{
Windows32::onDestroy();
}

I have tried searching up on the inte.net and looking for answers and I have tried the debugger

Answer 1

You have to implement constructor which creates Window32 from HWND . If you simply cast HWND to Window32* , then it could lead to segfault because you write to and read from memory that is outside the bounds of the area that hwnd points to. In other words, your cast will not automatically create Window32 from HWND . Here is my suggestion:

public:
    Windows32(HWND hWnd)
    {
        this->m_hwnd = hWnd;
        this->m_is_run = true;
    }

Use

Windows32 window(((LPCREATESTRUCT)lparam)->lpCreateParams);

instead

Windows32* window = (Windows32*)((LPCREATESTRUCT)lparam)->lpCreateParams;