Restricts read/write access to a file or portion of a file
Syntax
Lock #filenum [, record ]
Lock #filenum, [ start ] To end
Parameters
filenum
The file number used to
Open the file.
record
The record (
Random files) or byte position (
Binary files) to lock. If omitted, the entire file is locked.
start
The first record (
Random files) or byte position (
Binary files) to lock from. If omitted, the current record/byte position (
Seek(
filenum)) is used.
end
The last record (
Random files) or byte position (
Binary files) to lock to.
Description
Lock temporarily restricts access by other threads or programs to a file, or portion of a file, usually to allow safe writing to it.
After modifying the data, an
Unlock with the same parameters as the
Lock should be issued.
Example
'' e.g. locking a file, reading 100 bytes, and unlocking it.
'' To run, make sure there exists a file called 'file.ext'
'' in the current directory that is at least 100 bytes.
Dim array(1 To 100) As Integer
Dim f As Integer, i As Integer
f = FreeFile
Open "file.ext" For Binary As #f
Lock #f, 1 To 100
For i = 1 To 100
Get #f, i, array(i)
Next
Unlock #f, 1 To 100
Close #f
Differences from QB
See also