[Windows API] Listing the Files in a Directory，可用来数文件夹下有多少个子文件（夹）

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#include <windows.h>
#include <tchar.h>
#include <stdio.h>
#include <strsafe.h>
#pragma comment(lib, "User32.lib")

void DisplayErrorBox(LPTSTR lpszFunction);

int _tmain(int argc, TCHAR *argv[])
{
   WIN32_FIND_DATA ffd;
   LARGE_INTEGER filesize;
   TCHAR szDir[MAX_PATH];
   size_t length_of_arg;
   HANDLE hFind = INVALID_HANDLE_VALUE;
   DWORD dwError=;

   // If the directory is not specified as a command-line argument,
   // print usage.

   if(argc != )
   {
      _tprintf(TEXT("\nUsage: %s <directory name>\n"), argv[]);
      return (-);
   }

   // Check that the input path plus 3 is not longer than MAX_PATH.
   // Three characters are for the "\*" plus NULL appended below.

   StringCchLength(argv[], MAX_PATH, &length_of_arg);

   if (length_of_arg > (MAX_PATH - ))
   {
      _tprintf(TEXT("\nDirectory path is too long.\n"));
      return (-);
   }

   _tprintf(TEXT("\nTarget directory is %s\n\n"), argv[]);

   // Prepare string for use with FindFile functions.  First, copy the
   // string to a buffer, then append '\*' to the directory name.

   StringCchCopy(szDir, MAX_PATH, argv[]);
   StringCchCat(szDir, MAX_PATH, TEXT("\\*"));

   // Find the first file in the directory.

   hFind = FindFirstFile(szDir, &ffd);

   if (INVALID_HANDLE_VALUE == hFind)
   {
      DisplayErrorBox(TEXT("FindFirstFile"));
      return dwError;
   } 

   // List all the files in the directory with some info about them.

   do
   {
      if (ffd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
      {
         _tprintf(TEXT("  %s   <DIR>\n"), ffd.cFileName);
      }
      else
      {
         filesize.LowPart = ffd.nFileSizeLow;
         filesize.HighPart = ffd.nFileSizeHigh;
         _tprintf(TEXT("  %s   %ld bytes\n"), ffd.cFileName, filesize.QuadPart);
      }
   }
   while (FindNextFile(hFind, &ffd) != );

   dwError = GetLastError();
   if (dwError != ERROR_NO_MORE_FILES)
   {
      DisplayErrorBox(TEXT("FindFirstFile"));
   }

   FindClose(hFind);
   return dwError;
}

void DisplayErrorBox(LPTSTR lpszFunction)
{
    // Retrieve the system error message for the last-error code

    LPVOID lpMsgBuf;
    LPVOID lpDisplayBuf;
    DWORD dw = GetLastError(); 

    FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER |
        FORMAT_MESSAGE_FROM_SYSTEM |
        FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        dw,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPTSTR) &lpMsgBuf,
        , NULL );

    // Display the error message and clean up

    lpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT,
        (lstrlen((LPCTSTR)lpMsgBuf)+lstrlen((LPCTSTR)lpszFunction)+)*sizeof(TCHAR));
    StringCchPrintf((LPTSTR)lpDisplayBuf,
        LocalSize(lpDisplayBuf) / sizeof(TCHAR),
        TEXT("%s failed with error %d: %s"),
        lpszFunction, dw, lpMsgBuf);
    MessageBox(NULL, (LPCTSTR)lpDisplayBuf, TEXT("Error"), MB_OK); 

    LocalFree(lpMsgBuf);
    LocalFree(lpDisplayBuf);
}