新手请教Windows编程"KEYVIEW"程序

wolaicici

# include <windows.h>
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
     PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("KeyView");
HWND      hwnd;
MSG       msg;
WNDCLASS  wndclass;

    wndclass.cbClsExtra    = 0;
wndclass.cbWndExtra    = 0;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW);
wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hInstance     = hInstance;
wndclass.lpfnWndProc   = WndProc;
wndclass.lpszClassName = szAppName;
wndclass.lpszMenuName  = NULL;
wndclass.style         = CS_HREDRAW | CS_VREDRAW;

if (!RegisterClass (&wndclass))
{
  MessageBox (NULL, TEXT ("This program requires Windows NT!"),
   szAppName, MB_ICONERROR);
  return 0;
}

hwnd = CreateWindow (szAppName, TEXT ("Keyboard Message Viewer #1"), 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)
{
static int cxClientMax, cyClientMax, cxClient, cyClient, cxChar, cyChar;
static int cLinesMax, cLines;
static PMSG  pmsg;
static RECT  rectScroll;
static TCHAR szTop[] = TEXT ("Message Key Char *")
                     TEXT ("Repeat Scan Ext ALT Prev Tran");
static TCHAR szUnd[] = TEXT ("------- --- ------")
                     TEXT ("------ ---- --- --- ---- ----");
static TCHAR * szFormat[2] = {
  TEXT ("%-13s %3d %-15s%c%6u %4d %3s %3s %4s %4s"),
  TEXT ("%-13s            0x%04X%1s%c %6u %4d %ss %3s %4s %4s")};
    static TCHAR * szYes  = TEXT ("Yes");
static TCHAR * szNo   = TEXT ("No");
static TCHAR * szDown = TEXT ("Down");
static TCHAR * szUp   = TEXT ("Up");
static TCHAR * szMessage[] = {
  TEXT ("WM_KEYDOWN"),     TEXT ("WM_KEYUP"),
  TEXT ("WM_CHAR"),        TEXT ("WM_DEADCHAR"),
  TEXT ("WM_SYSKEYDOWN"),  TEXT ("WM_SYSKEYUP"),
  TEXT ("WM_SYSCHAR"),     TEXT ("WM_SYSDEADCHAR"),};
    HDC          hdc;
int          i, iType;
PAINTSTRUCT  ps;
TCHAR        szBuffer[128], szKeyName[32];
TEXTMETRIC  tm;
switch (message)
{
case WM_CREATE:
case WM_DISPLAYCHANGE:
  cxClientMax = GetSystemMetrics (SM_CXMAXIMIZED);
  cyClientMax = GetSystemMetrics (SM_CYMAXIMIZED);
  hdc = GetDC (hwnd);
  SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT));
  GetTextMetrics (hdc, &tm);
  cxChar = tm.tmAveCharWidth;
  cyChar = tm.tmHeight;
  ReleaseDC (hwnd, hdc);
  if (pmsg)
   free (pmsg);
  cLinesMax = cyClientMax / cyChar;
  pmsg = malloc (cLinesMax * sizeof (MSG));
  cLines = 0;
case WM_SIZE:
  if (message == WM_SIZE)
  {
   cxClient = LOWORD (lParam);
   cyClient = HIWORD (lParam);
  }
  rectScroll.left = 0;
  rectScroll.right = cxClient;
  rectScroll.top = cyChar;
  rectScroll.bottom = cyChar * (cyClient / cyChar);
  InvalidateRect (hwnd, NULL, TRUE);
  return 0;
case WM_KEYDOWN:
case WM_KEYUP:
case WM_CHAR:
case WM_DEADCHAR:
case WM_SYSKEYDOWN:
case WM_SYSKEYUP:
case WM_SYSCHAR:
case WM_SYSDEADCHAR:
  for (i = cLinesMax - 1; i > 0; i--)
  {
   pmsg[i] = pmsg[i-1];
  }
  pmsg[0].hwnd = hwnd;
  pmsg[0].message = message;
  pmsg[0].wParam = wParam;
  pmsg[0].lParam = lParam;
  cLines = min (cLines + 1, cLinesMax);
  ScrollWindow (hwnd, 0, -cyChar, &rectScroll, &rectScroll);
  break;
case WM_PAINT:
  hdc = BeginPaint (hwnd, &ps);
  SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT));
  SetBkMode (hdc, TRANSPARENT);
  TextOut (hdc, 0, 0, szTop, lstrlen (szTop));
  TextOut (hdc, 0, 0, szUnd, lstrlen (szUnd));
  for (i=0; i < min(cLines, cyClient / cyChar - 1); i++)
  {
   iType = pmsg[i].message == WM_CHAR ||
        pmsg[i].message == WM_SYSCHAR ||
     pmsg[i].message == WM_DEADCHAR ||
     pmsg[i].message == WM_SYSDEADCHAR;
   GetKeyNameText (pmsg[i].lParam, szKeyName,
    sizeof (szKeyName) / sizeof (TCHAR));
   TextOut (hdc, 0, (cyClient / cyChar - 1 - i) * cyChar, szBuffer,
    wsprintf (szBuffer, szFormat [iType],
              szMessage [pmsg[i].message - WM_KEYFIRST],
        pmsg[i].wParam,
        (PTSTR) (iType ? TEXT (" ") : szKeyName),
        (TCHAR) (iType ? pmsg[i].wParam : ' '),
        LOWORD (pmsg[i].lParam),
        HIWORD (pmsg[i].lParam) & 0xFF,
        0x01000000 & pmsg[i].lParam ? szYes  : szNo,
        0x20000000 & pmsg[i].lParam ? szYes  : szNo,
        0x40000000 & pmsg[i].lParam ? szDown : szUp,
        0x80000000 & pmsg[i].lParam ? szUp   : szDown));
  }
  EndPaint (hwnd, &ps);
  return 0;
case WM_DESTROY:
  PostQuitMessage (0);
  return 0;
}
return DefWindowProc (hwnd, message, wParam, lParam);

}

--------------------Configuration: KEYVIEW1 - Win32 Debug--------------------
Compiling...
KEYVIEW1.CPP
D:\Program Files\Microsoft Visual Studio\MyProjects\KEYVIEW1\KEYVIEW1.CPP(100) : error C2440: '=' : cannot convert from 'void *' to 'struct tagMSG *'
        Conversion from 'void*' to pointer to non-'void' requires an explicit cast
执行 cl.exe 时出错.
KEYVIEW1.OBJ - 1 error(s), 0 warning(s)

大家好，以上是新手自己从Window书上抄的代码，研究了半天但还是看不懂错误提示的意思。请高手指点一下，非常感谢！

liufei_vip

pmsg =(struct tagMSG *)malloc (cLinesMax * sizeof (MSG));
PS:你给的代码不全吧。。。

苹果沃珂

使用malloc分配的动态内存是要指定数据类型：
pmsg =  (PMSG)malloc (cLinesMax * sizeof (MSG));

风之残月

pmsg = malloc (cLinesMax * sizeof (MSG))改为pmsg = (PMSG)malloc (cLinesMax * sizeof (MSG))试试

wolaicici

原来是这样的，可以运行了，谢谢楼上几位高手{:1_1:}