virtual void LockRange( DWORD dwPos, DWORD dwCount )
throw( CFileException );
dwPos
The byte offset of the start of the byte range to lock.
dwCount
The number of bytes in the range to lock.
Locks a range of bytes in an open file, throwing an exception if the file is already locked. Locking bytes in a file prevents access to those bytes by other processes. You can lock more than one region of a file, but no overlapping regions are allowed.
When you unlock the region, using the UnockRange member function, the byte range must correspond exactly to the region that was previously locked. The LockRange function does not merge adjacent regions; if two locked regions are adjacent, you must unlock each region separately.
Under MS-DOS, you must load SHARE.EXE; otherwise, the function throws a CFileException object.
Note:
This function is not available for the CMemFile-derived class.
extern DWORD dwPos;
extern DWORD dwCount;
extern CFile cfile;
cfile.LockRange( dwPos, dwCount );