在编写一个Winodw练习题遇到一个问题? 400 报错

#include<windows.h>
#include<stdio.h>
LRESULT CALLBACK WindowProc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam);

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

//设计窗口
WNDCLASS wndclass;
wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);/*HBRBACKGEOUND调用了GETSTOCKOBJECT函数HBRACKGROUND
GETSTOCKOBJECT(HBRUSH)类型转换*/
wndclass.hCursor=LoadCursor(NULL,IDI_APPLICATION); /*HCURSOR调用LOADCURSOR函数*/
wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);/*HICON调用了LOADICON函数*/
wndclass.hInstance=hInstance;
wndclass.lpfnWndProc=WindowProc;
wndclass.lpszClassName="WIND";
wndclass.lpszMenuName=NULL;
wndclass.style=CS_HREDRAW|CS_VREDRAW;
RegisterClass(&wndclass);

//创建窗口，定义一个变量用来保存成功创建窗口后返回的句柄
HWND hwnd;
hwnd=CreateWindow("WIND","aa",WS_OVERLAPPEDWINDOW,0,0,400,200,NULL,NULL,hInstance,NULL);//hWndParent,hMenu,不明白的句柄

//显示刷新窗口
ShowWindow (hwnd,SW_SHOWNORMAL);
UpdateWindow(hwnd);

//定义消息结构
MSG msg;
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}

    //编写窗口过程
LRESULT CALLBACK WindowProc(HWND hwnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
   switch(uMsg)
   {
    char szChar[20];
    sprintf(szChar,"char code is %d",wParam);
    MessageBox(hwnd,szChar,"char ",0);
    break;
   case WM_LBUTTONDOWN:
    MessageBox(hwnd,"mouse clicked","message",0);
    HDC hdc;
    hdc=GetDC(hwnd);
    TextOut(hdc,0,50,"程序之家",strlen ("程序之家"));
    break;
   case WM_PAINT:
    HDC hDC;
    PAINTSTRUCT ps;
    hDC=BeginPaint(hwnd,&ps);
    TextOut(hDC,0,0,"aa",strlen("aa"));
    EndPaint(hwnd,&ps);
    break;
   case WM_CLOSE:
    if(IDYES==MessageBox(hwnd,"是否真的结束","message",MB_YESNO))
    {
     DestroyWindow(hwnd);
    }
    break;
   case WM_DESTROY:
    PostOuitMessage(0);
    break;