how can I delete all that string instead of writing nothing? because nothing actually means a line with nothing, but the line exists. I want it to no longer exist!
Dim textfile() As String = IO.File.ReadAllLines(My.Application.Info.DirectoryPath + ("\textfile.txt"))
For i As Integer = 0 To textfile.Count - 1
If textfile(i).Length > 1 Then
textfile(i) = Nothing 'here i want to delete
End if
Next
You can use LINQ to select only lines that are not empty:
Dim textfile = IO.File.ReadAllLines(IO.Path.Combine(My.Application.Info.DirectoryPath, "textfile.txt"))
Dim filteredTextFile = textfile.Where(Function(line) Not String.IsNullOrWhitespace(line)).ToArray()
Fiddle: https://dotnetfiddle.net/nUpjEH
You need to filter out the empty lines, and write to a file. The accepted answer does the first part of this, so here is the complete solution
Dim textFile = File.ReadAllLines("filename.txt")
Dim fixedLines = textFile.Where(Function(line) Not String.IsNullOrWhiteSpace(line))
File.WriteAllLines("filename.txt", fixedLines)
@HansPassant pointed out in a comment that this is not the most efficient solution. Here is another way to do it using StreamReader / StreamWriter
Dim lines As New List(Of String)()
Using sr As New StreamReader("filename.txt")
While Not sr.EndOfStream
Dim line = sr.ReadLine()
If Not String.IsNullOrWhiteSpace(line) Then lines.Add(line)
End While
End Using
Using sw As New StreamWriter("filename.txt")
For Each line In lines
sw.WriteLine(line)
Next
End Using
However, using a 1kb file ~1000 line file with a few empty lines, my system takes about 18ms for the first method, and 18 ms for the second (each averaged 1000 times). So at least in my system, in this case, there isn't much of a difference. See https://designingefficientsoftware.wordpress.com/2011/03/03/efficient-file-io-from-csharp/ for further analysis if efficiency is a concern.
File.ReadAllLines must be used - if File.ReadLines were used then this code would fail.
list<string> you just write line into the sw as you read it?
According to this If textfile(i).Length > 1 Then you seem want only short lines to remain. And you setting nothing only to long ones
Do this using LINQ
Dim onlyShortLines() as String =
textfile.Where(Func(x) x.Length = 1).Select(Func(x) x).ToArray()
Func(x) should be Function(x). Finally, there's no need for .Select(Function(x) x) that is just redundant.null should be set on the lines longer than 1 character. If you read the Q again and then the code provided - combine the 2 and look - OP takes lines, selects those longer than 1 and sets them to null. Then in the question it asks how to get rid of those. If you read the question and the code- you will see that my answer is correct. I did exactly what OP asked for. It is OP had not asked the Q correctly given the code