My C++ window program run but i cannot see - c++

Question

Below is the code. When run, there's no window shown, and there are no error messages. What did I do wrong?
//WinApp.h
#pragma once
#include<Windows.h>
class WinApp
{
private: HWND hWnd;
MSG msg;
static WinApp *instance;
public:
WinApp(void);
~WinApp(void);
void CreateWnd(HINSTANCE hInstance, int iCmdShow);
int Run(HINSTANCE hInstance, int iCmdShow);
void Release();
static HRESULT CALLBACK WndProc(HWND hwnd, UINT imsg, WPARAM wParam, LPARAM lParam);// window proc
static WinApp* GetInstance();
};
//WinApp.cpp
#include "WinApp.h"
#include<Windows.h>
WinApp::WinApp(void)
{
hWnd=NULL;
ZeroMemory(&msg,sizeof(MSG));
}
WinApp::~WinApp(void)
{
delete hWnd;
}
void WinApp::CreateWnd(HINSTANCE hInstance, int iCmdShow){
WNDCLASSEX WndClassex;
ZeroMemory(&WndClassex, sizeof(WNDCLASSEX));
WndClassex.cbSize=sizeof(WNDCLASSEX);
WndClassex.hCursor=LoadCursor(NULL, IDC_ARROW);
WndClassex.hIcon=LoadIcon(NULL, IDI_APPLICATION);
WndClassex.hbrBackground=(HBRUSH) GetStockObject(WHITE_BRUSH);
WndClassex.hInstance=hInstance;
WndClassex.style=CS_HREDRAW|CS_VREDRAW;
WndClassex.lpszClassName=L" ";
WndClassex.lpszMenuName=NULL;
WndClassex.lpfnWndProc=&WinApp::WndProc;
RegisterClassEx(&WndClassex);
hWnd=CreateWindowEx(0,
L" ",
L"UNUSUAL",
WS_CAPTION|WS_MINIMIZEBOX|WS_SYSMENU|WS_THICKFRAME,
0,
0,
512,
512,
NULL,
NULL,
hInstance,
NULL
);
ShowWindow(hWnd, SW_RESTORE);
UpdateWindow(hWnd);
}
void WinApp::Release(){
delete this;
}
int WinApp::Run(HINSTANCE hInstance, int iCmdShow){
this->CreateWnd(hInstance, iCmdShow);
while(GetMessage(&msg, NULL, 0, 0)){
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int)msg.wParam;
}
WinApp* WinApp::instance=0;
WinApp* WinApp::GetInstance(){
if(instance==NULL){
instance=new WinApp;
}
return instance;
}
HRESULT WinApp::WndProc(HWND hwnd, UINT imsg,WPARAM wParam, LPARAM lParam ){
switch (imsg)
{
case WM_PAINT:
HDC hdc;
PAINTSTRUCT ps;
RECT rect;
hdc = BeginPaint (hwnd, &ps);
GetClientRect (hwnd, &rect);
FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOW+1));
EndPaint (hwnd, &ps);
break;
case WM_QUIT:
PostQuitMessage(0);
WinApp::GetInstance()->Release();
break;
default: DefWindowProc(hwnd, imsg, wParam, lParam);
break;
}
return 0;
}
//main.cpp
#include<Windows.h>
#include"WinApp.h"
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,LPSTR lpszCmdLine, int iCmdShow){
WinApp::GetInstance()->Run(hInstance, iCmdShow);
return 0;
}

Answer 1

There are many things wrong with your code.
But apart from that, the reason why your window is not showing up is because WinApp::WndProc doesn't return DefWindowProc's result.
So simply change
default:
DefWindowProc(hwnd, imsg, wParam, lParam);
break;
to
default:
return DefWindowProc(hwnd, imsg, wParam, lParam);