CFile::LockRange (MFC)

Locks a range of bytes in an open file, throwing an exception if the file is already locked.

virtual void LockRange(
   ULONGLONG dwPos,
   ULONGLONG dwCount 
);

Parameters

dwPos

The byte offset of the start of the byte range to lock.

dwCount

The number of bytes in the range to lock.

Remarks

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 UnlockRange 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.

Note   This function is not available for the CMemFile-derived class.

Example

//example for CFile::LockRange
extern ULONGLONG dwPos;
extern ULONGLONG dwCount;
extern CFile cfile;
cfile.LockRange( dwPos, dwCount );

See Also

CFile Overview | Class Members | Hierarchy Chart | CFile::UnlockRange