I need to read all content of a file but keep only some of the content and append new content. So I tried to use READLINES filter the lines I need to keep then rewrite the file with the kept lines and new ones:
Dim paramLines As IEnumerable
paramLines = File.ReadLines(Path & "X.ini")
Dim paramFile As StreamWriter = New StreamWriter(Path & "X.ini",append:=False)
For Each paramline In paramLines
if condition_iskeepIt then paramFile.WriteLine(paramline)
Next ' paramLine
...write revised lines
However, this gives an error on the third line: System.IO.IOException: 'The process cannot access the file '...\X.ini' because it is being used by another process.'
What is holding the "process"? How do we get it to release?
File.ReadLines loads the file lazily. To load the lines of the file fully into memory, you can use File.ReadAllLines:
Dim paramLines As String() = File.ReadAllLines(Path & "X.ini")
Using paramFile As New StreamWriter(Path & "X.ini", append:=False)
' …
End Using
It is important to note that ReadAllLines loads all the file data in memory and thus (if the file is big) you will see a surge in the memory used by your application and a noticeable delay while the file is loaded.