LOCK

LOCK([#] filenumber [,recordrange])

Locks access to parts of a file for other processes.

filenumber	The number of the file (Integer).
recordrange	(Optional) Refers to a range of records (or bytes) that are to be locked.

REMARKS

* Prevents another process from accessing all or part of the open file that corresponds to the filenumber argument.
* You can use the UNLOCK statement to control access to a file.
* The equivalent .NET function is [[Microsoft.VisualBasic.FileSystem.Lock]]
* For the Microsoft documentation refer to learn.microsoft.com

Sub Testing() 

Dim MyRecord As udtRecord 
Dim RecordNumber As Integer 

'Open "C:\Temp\MyText.txt" For Output As #1 'Close #1 '
'Open "C:\Temp\MyText.txt" For Binary As #1 'RecordNumber = 1 'MyRecord.ID = "001"
'MyRecord.Name = "Name1"
'Put #1, , MyRecord
'MyRecord.ID = "002"
'MyRecord.Name = "Name2"
'Put #1, , MyRecord
'Close #1

Open "C:\Temp\MyText.txt" For Binary Shared As #1 Len = Len(MyRecord) 

RecordNumber = 1                 ' Define record number.  
Lock #1, RecordNumber            ' Lock record.  
Get #1, RecordNumber, MyRecord   ' Read record.  
MyRecord.ID = 111                ' Modify record.  
MyRecord.Name = "New Name1" 
Put #1, RecordNumber, MyRecord   ' Write modified record.  
Unlock #1, RecordNumber          ' Unlock current record.  
Close #1                         ' Close file.  

End Sub