求大家帮我看一下程序错在哪？静茹窗口的是鼠标不是箭头，并且程序好像陷入了死循环

#include"windows.h"
#include"stdio.h"
#include"tchar.h"

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


int WINAPI WinMain(
  HINSTANCE hInstance,
  HINSTANCE hPrevInstance,
  LPSTR lpCmdLine,
  int nShowCmd )
{
    BOOL msg_flag;
    MSG msg;
    HWND hwnd;
    WNDCLASS wndcls;

    wndcls.cbClsExtra=0;
    wndcls.cbWndExtra=0;
    wndcls.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
    wndcls.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndcls.hIcon=LoadIcon(NULL,IDI_APPLICATION);
    wndcls.hInstance=hInstance;
    wndcls.lpfnWndProc=WndProc;
    wndcls.lpszClassName=_T("C PROGRAM DESIGN");
    wndcls.lpszMenuName=NULL;
    wndcls.style=CS_HREDRAW|CS_VREDRAW;
    RegisterClass(&wndcls);
    hwnd=CreateWindow(_T("C PROGRAM DESIGN"),_T("HELLO 大家好!"),WS_OVERLAPPEDWINDOW,
         CW_USEDEFAULT,0, CW_USEDEFAULT,0,NULL,NULL,hInstance,NULL);
    ShowWindow(hwnd,SW_NORMAL);
    UpdateWindow(hwnd);
    msg_flag=GetMessage(&msg,hwnd,0,0);
    while(msg_flag)
    {
        if(msg_flag==-1)
            return -1;
        else
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
}

LRESULT CALLBACK WndProc(
    HWND hwnd,
    UINT msg,
    WPARAM wparam,
    LPARAM lparam
)
{
    HDC hdc;
    PAINTSTRUCT ps;

    switch(msg)
    {
    case WM_CHAR:
        MessageBox(hwnd,TEXT("这是对话空"),_T("您好！"),0);
        break;
    case WM_LBUTTONDOWN:
        MessageBox(hwnd,TEXT("这是对话空"),_T("您好！"),0);
        hdc=GetDC(hwnd);
        TextOut(hdc,0,0,_T("这是程序员之家"),strlen("这是程序员之家"));
        ReleaseDC(hwnd,hdc);
        break;
    case WM_PAINT:
        HDC hdc;
        hdc=BeginPaint(hwnd,&ps);
        TextOut(hdc,0,0,_T("这是程序员之家"),strlen("这是程序员之家"));
        EndPaint(hwnd,&ps);
        ReleaseDC(hwnd,hdc);
        break;
    case WM_CLOSE:
        if(IDYES==MessageBox(hwnd,TEXT("是否真的结束？"),_T("message"),MB_YESNO))
            DestroyWindow(hwnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd,msg,wparam,lparam);
    return 0;
    }
}