函数ReadDirectoryChangesW在VC6.0下调用时总是总是报没有定义？

函数ReadDirectoryChangesW在VC6.0下调用时总是总是报没有定义？

这是UNICODE版本的函数，你需要定义_UNICODE或UNICODE宏才能有效。

最好两个都定义。 :D

如何定义_UNICODE或UNICODE宏？能给我点例程吗？

如何定义_UNICODE或UNICODE宏？能给我点例程吗？

你可以不定义，只要把后面的一个W去掉即可，即：
ReadDirectoryChanges
如果硬要定义的话，需要在#include \"windows.h\"加上
#define _UNICODE
或者在Prject->Settings->C/C->Preprosessor definitions中加上
_UNICODE或UNICODE即可。

[编辑 -  11/9/02 by  Tom_lyd]

Please try  #include <TCHAR.H>

MSDN的例子：
FWATCH.C
/**********************************************************************    File name: fwatch.c        Main source file for sample demonstrating use of file change       notification APIs.     Functions:        CheckChangedFile()      - Gets and displays change information       HandleDirectoryChange() - Watch function       WatchDirectories()      - Starts the watch       main()                  - Program main      Written by Microsoft Product Support Services, Windows Developer Support.    Copyright 1996 - 1998 Microsoft Corporation. All rights reserved. **********************************************************************/
#define UNICODE
 #include <stdio.h> #include <stdlib.h> #include <conio.h> #include <windows.h>  #define MAX_DIRS    10 #define MAX_FILES   255 #define MAX_BUFFER  4096  // this is the all purpose structure that contains   // the interesting directory information and provides // the input buffer that is filled with file change data typedef struct _DIRECTORY_INFO { HANDLE      hDir; TCHAR       lpszDirName[MAX_PATH]; CHAR        lpBuffer[MAX_BUFFER]; DWORD       dwBufLength; OVERLAPPED  Overlapped; }DIRECTORY_INFO, *PDIRECTORY_INFO, *LPDIRECTORY_INFO;  DIRECTORY_INFO  DirInfo[MAX_DIRS];        // Buffer for all of the directories TCHAR           FileList[MAX_FILES*MAX_PATH];   // Buffer for all of the files DWORD           numDirs;   /**********************************************************************    CheckChangedFile()     Purpose:       This function prints out information when one of the files we       are watching is changed.     Parameters:        LPDIRECTORY_INFO lpdi - Information about the watched directory       PFILE_NOTIFY_INFORMATION lpfni - Information about modified file      Return Value:       None     Comments:  ********************************************************************/ void WINAPI CheckChangedFile( LPDIRECTORY_INFO lpdi,                               PFILE_NOTIFY_INFORMATION lpfni) {     TCHAR      szFullPathName[MAX_PATH];     TCHAR      *p;     HANDLE     hFile;     FILETIME   LocalFileTime;     SYSTEMTIME SystemTime;     BY_HANDLE_FILE_INFORMATION FileInfo;      p = FileList;      while(*p && lstrcmpi(p,lpfni->FileName))         p+=(lstrlen(p)+1);      if(*p)     {         lstrcpy( szFullPathName, lpdi->lpszDirName );         lstrcat( szFullPathName, L\"\\\\\" );         lstrcat( szFullPathName, lpfni->FileName );          // we assume that the file was changed, since          // that is the only thing we look for in this sample         wprintf( L\"%s changed,\", szFullPathName );          hFile=CreateFile( szFullPathName,                           GENERIC_READ,                           FILE_SHARE_READ,                           NULL,                           OPEN_EXISTING,                           FILE_FLAG_SEQUENTIAL_SCAN,                           0);          GetFileInformationByHandle( hFile, &FileInfo );          FileTimeToLocalFileTime( &(FileInfo.ftLastWriteTime), &LocalFileTime );          FileTimeToSystemTime( &LocalFileTime, &SystemTime );          wprintf( L\" Size = %d bytes,\", FileInfo.nFileSizeLow );         wprintf( L\" Last Access = %02d/%02d/%02d %02d:%02d:%02d\",                  SystemTime.wMonth,                  SystemTime.wDay,                  SystemTime.wYear,                  SystemTime.wHour,                  SystemTime.wMinute,                  SystemTime.wSecond );          CloseHandle( hFile );          wprintf( L\"\\n\" );     } }   /**********************************************************************    HandleDirectoryChanges()     Purpose:       This function receives notification of directory changes and       calls CheckChangedFile() to display the actual changes. After       notification and processing, this function calls       ReadDirectoryChangesW to reestablish the watch.     Parameters:        HANDLE hCompPort - Handle for completion port      Return Value:       None     Comments:  ********************************************************************/ void WINAPI HandleDirectoryChange( DWORD dwCompletionPort ) {     DWORD numBytes;     DWORD cbOffset;     LPDIRECTORY_INFO di;     LPOVERLAPPED lpOverlapped;     PFILE_NOTIFY_INFORMATION fni;      do     {         // Retrieve the directory info for this directory         // through the completion key         GetQueuedCompletionStatus( (HANDLE) dwCompletionPort,                                    &numBytes,                                    (LPDWORD) &di,                                    &lpOverlapped,                                    INFINITE);          if ( di )         {              fni = (PFILE_NOTIFY_INFORMATION)di->lpBuffer;              do             {                 cbOffset = fni->NextEntryOffset;                  if( fni->Action == FILE_ACTION_MODIFIED )                     CheckChangedFile( di, fni );                  fni = (PFILE_NOTIFY_INFORMATION)((LPBYTE) fni + cbOffset);              } while( cbOffset );              // Reissue the watch command             ReadDirectoryChangesW( di->hDir,di->lpBuffer,                                    MAX_BUFFER,                                    TRUE,                                    FILE_NOTIFY_CHANGE_LAST_WRITE,                                    &di->dwBufLength,                                    &di->Overlapped,                                    NULL);         }      } while( di );   }   /**********************************************************************    WatchDirectories()     Purpose:       This function implements the ReadDirectoryChangesW API for       indicated directories. For each directory watched, a thread       is created which waits for changes to the directory. This       function waits for the user to input \'q\', then cleans up and       quits.     Parameters:        HANDLE hCompPort - Handle for completion port      Return Value:       None  ********************************************************************/ void WINAPI WatchDirectories( HANDLE hCompPort ) {     DWORD   i;     DWORD   tid;     HANDLE  hThread;       // Start watching each of the directories of interest      for (i=0;i<numDirs;i++)     {         ReadDirectoryChangesW( DirInfo.hDir,                                DirInfo.lpBuffer,                                MAX_BUFFER,                                TRUE,                                FILE_NOTIFY_CHANGE_LAST_WRITE,                                &DirInfo.dwBufLength,&DirInfo.Overlapped,                                NULL);     }      // Create a thread to sit on the directory changes      hThread = CreateThread( NULL,                             0,                             (LPTHREAD_START_ROUTINE) HandleDirectoryChange,                             hCompPort,                             0,                             &tid);      // Just loop and wait for the user to quit      while (getch() != \'q\');      // The user has quit - clean up      PostQueuedCompletionStatus( hCompPort, 0, 0, NULL );      // Wait for the Directory thread to finish before exiting      WaitForSingleObject( hThread, INFINITE );      CloseHandle( hThread ); }   /**********************************************************************    main()     Purpose:       Main entry-point for fwatch sample. This function reads an .ini       file (fwatch.ini) to determine which directories and files to           watch. For each directory watched some information is gathered       and stored.     Return Value:  (see errors.h for description)       None     Comments:  ********************************************************************/ void main(int argc, char *argv[]) {      TCHAR   *p,*q;                          // Temporary String Pointer     HANDLE  hCompPort=NULL;                 // Handle To a Completion Port     DWORD   i;                              // You always need an I.     TCHAR   DirList[MAX_DIRS*MAX_PATH];     // Buffer for all of the directories     TCHAR   IniFile[MAX_PATH];     TCHAR   FilePath[MAX_PATH];     HANDLE  hFile;      GetCurrentDirectory( MAX_PATH, IniFile );      lstrcat( IniFile, L\"\\\\fwatch.ini\" );      GetPrivateProfileString( L\"Directories\",                              NULL,                              NULL,                              DirList,                              MAX_DIRS*MAX_PATH,                              IniFile );      GetPrivateProfileString( L\"Files\",                              NULL,                              NULL,                              FileList,                              MAX_FILES*MAX_PATH,                              IniFile );      wprintf( L\"Watching these directories:\\n\" );      // First, walk through the raw list and count items, creating     // an array of handles for each directory     for (p=DirList;*p!=\'\\0\';numDirs++,p+=(lstrlen(p)+1))     {