◄Summary► ◄Example► ◄Up► ◄Contents► ◄Index► ◄Back► ─────Run-Time Library────────────────────────────────────────────────────── The _locking function locks or unlocks <nbyte> bytes of the file specified by <handle>. Locking bytes in a file prevents access to those bytes by other processes in a networked or multiuser system. All locking or unlocking begins at the current position of the file pointer and proceeds for the next <nbyte> bytes, or to the end of the file. It is possible to lock bytes past the end of the file. The <mode> argument specifies the locking action to be performed. It must be one of the following manifest constants: _LK_LOCK _LK_NRBLCK _LK_UNLCK _LK_NBLCK _LK_RLCK More than one region of a file can be locked, but no overlapping regions are allowed. When a region of a file is unlocked, it must correspond to a region that was previously locked. The _locking function does not merge adjacent regions; if two locked regions are adjacent, each region must be unlocked separately. Regions should be locked only briefly and should be unlocked before closing a file or exiting the program. The _locking function should be used only with DOS versions 3.0 or later; it has no effect under earlier versions of DOS. Note that under DOS versions 3.0 and 3.1, the files locked by a parent process may become unlocked when one of its children exits. File sharing must be loaded to use the locking function. Under DOS versions 3.0 and higher, you may need to use the SHARE program provided with DOS to enable file sharing. Check documentation for your networking software and the DOS SHARE program for details. Return Value The _locking function returns 0 if it is successful. A return value of -1 indicates failure, and errno is set to EACCES, EBADF, EDEADLOCK, or EINVAL. -♦-