C++编程中设置文件长度的方法

转自：http://blog.csdn.net/rrrfff/article/details/6705685

 bool SetFileLength(const char *FilePath, off_t Length)
 {
 #ifdef WIN32
     System::IO::FileStream *File = System::IO::File::Open(Length, File::OpenMode, File::AllAccess);
     if (!File)
     {
         return false;
     }
     /// <summary>
     /// 表达式调用 File->SetLength() 方法
     /// 该方法的底层实现是调用NtSetInformationFile
     /// 并通过 FILE_END_OF_FILE_INFORMATION 结构来设置文件长度
     /// 该方法的优势是可以直接设置 LONGLONG 型的长度
     /// </summary>
     File->Length = Length;
     delete File;
     return true;
     //参考资料
     //http://msdn.microsoft.com/en-us/library/ff567096(v=VS.85).aspx
 #else
     int fd = open(FilePath, O_RDWR);
     /// <summary>
     /// -1 if an error occurred
     /// </summary>
     if (fd == -)
     {
         return false;
     }
     /// <summary>
     /// On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
     /// </summary>
     return ftruncate(fd, Length) == ;
     //参考资料
     //http://api.taocpp.com/doc/path/linux系统调用/文件读写/ftruncate/
     //http://linux.die.net/man/2/ftruncate
 #endif
 }