关于PlaySound的有关问题

#include <Windows.h>
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain( __in HINSTANCE hInstance, __in_opt HINSTANCE hPrevInstance, __in LPSTR szCmdLine, __in int iCmdShow )
{
    static TCHAR szAppName[] = TEXT("HelloWin");
    HWND hwnd;
    MSG msg;
    WNDCLASS wndclass;
    wndclass.style = CS_HREDRAW|CS_VREDRAW;
    wndclass.lpfnWndProc = WndProc;
    wndclass.cbClsExtra = 0;
    wndclass.cbWndExtra = 0;
    wndclass.hInstance = hInstance;
    wndclass.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    wndclass.hCursor = LoadCursor(NULL,IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;

    if(!RegisterClass(&wndclass))
    {
        MessageBox(NULL,TEXT("This program requires windows nt!"),szAppName,MB_ICONERROR);
        return 0;
    }
    hwnd = CreateWindow(szAppName,
        TEXT("The Hello Program"),
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        NULL,
        NULL,
        hInstance,
        NULL);
    ShowWindow(hwnd,iCmdShow);
    UpdateWindow(hwnd);
    while (GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    RECT rect;
    switch(message)
    {
    case WM_CREATE:
        PlaySound(TEXT("hellowin.wav"),NULL,SND_FILENAME|SND_ASYNC);
        return 0;
    case WM_PAINT:
        hdc = BeginPaint(hwnd,&ps);
        GetClientRect(hwnd,&rect);
        DrawText(hdc,TEXT("Hello,Windows 98!"),-1,&rect,DT_SINGLELINE|DT_CENTER|DT_VCENTER);
        EndPaint(hwnd,&ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}