How to read file and compare with string ?

Question

Hello everybody

I have a file text , more line

This is my text :

THis is msdn
http://social.msdn.microsoft.com

That is msdn

http://social.msdn.microsoft.com

Here is msdn

http://social.msdn.microsoft.com

Now, I want to find "social.msdn.microsoft.com" and delete it

This is result  of file after delete

THis is msdn
That is msdn
Here is msdn 

How to do it ? I`m try

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim path As String = "D:\Demo\test"
        Dim sr As StreamReader = New StreamReader(path, True)

        Dim sInputLine = sr.ReadLine()
        Do Until sInputLine Is Nothing
            sInputLine = sr.ReadLine()
            If sInputLine = "social.msdn.microsoft.com" Then
                sInputLine.Remove()
            End If
        Loop
    End Sub

Can you help me . Thank so much.

Answer 1

Hello headshot9x9,

Hello everybody

I have a file text , more line

This is my text :

THis is msdn
http://social.msdn.microsoft.com

That is msdn

http://social.msdn.microsoft.com

Here is msdn

http://social.msdn.microsoft.com

Now, I want to find "social.msdn.microsoft.com" and delete it

This is result  of file after delete

THis is msdn
That is msdn
Here is msdn 

How to do it ? I`m try

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim path As String = "D:\Demo\test"
        Dim sr As StreamReader = New StreamReader(path, True)

        Dim sInputLine = sr.ReadLine()
        Do Until sInputLine Is Nothing
            sInputLine = sr.ReadLine()
            If sInputLine = "social.msdn.microsoft.com" Then
                sInputLine.Remove()
            End If
        Loop
    End Sub

Can you help me . Thank so much.

use Equals method ,

If sInputLine.Equals("social.msdn.microsoft.com") Then
                sInputLine.Remove()
            End If

Regards.

---

• Carmelo La Monica
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Answer 2

Hi Carmelo La Monica

First , thank you . Then i have two problem :

1) how to delete that line , so that my file only

THis is msdn
That is msdn
Here is msdn 

2)the case file in this text file is not there to do so?

Answer 3

You can't update a text file like that.  You need to write a new file.

Dim path As String = "D:\Demo\test"
Dim Lines As String() = File.ReadAllLines(path)

File.Delete(path)

For Each Line As String In Lines
    If Line <>"social.msdn.microsoft.com" Then
    File.AppendAllText(path, Line & Environment.NewLine)
Next Line

Answer 4

Hi Acamar

Do you think it useful in this case, or do we just delete the line, at which the string found. If the case file is too large, delete and record the work is time consuming
Hope you respond soon

finding your way just in case the search string are written, assuming it is behind a number of other characters do not do it this way

THis is msdn
http://social.msdn.microsoft.com
That is msdn 
http://social.msdn.microsoft.com
Here is msdn 
http://social.msdn.microsoft.com

you can try with my purpose

This is result

THis is msdn
That is msdn
Here is msdn

Thank you

Answer 5

OH, we can try

   Dim path As String = "E:\Demo\test"
        Dim Lines As String() = File.ReadAllLines(path)

        File.Delete(path)

        For Each Line As String In Lines
            If Equals(Line, "google.com.vn") = False Then
                File.AppendAllText(path, Line & Environment.NewLine)
            End If
        Next Line

Answer 6

I find error in at line

File.Delete(path)

This is show error

The process cannot access the file E:\Demo\test because it is being used by another process

And this is my code

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    
 Dim path As String = "D:\Demo\test"
        Dim sr As StreamReader = New StreamReader(path, True)
        Dim Lines As String() = File.ReadAllLines(path)

        File.Delete(path)

        For Each Line As String In Lines
            If Equals(Line, "google.com.vn") = False Then
                File.AppendAllText(path, Line & Environment.NewLine)
            End If
        Next Line

    End Sub

can you see it

Answer 7

As you don't use the streamreader, you can delete the declaration line.

---

Armin

Answer 8

I misread your input file format.   Change the test to

    If Not Line.EndsWith("social.msdn.microsoft.com") Then

to meet your original description.  I'm not sure where Google has come from, but you might be suggesting that there is a range of different lines that you want to ignore.  For instance, the test might need to be:

    If Line.SubString(0,5) <> "http:" Then

It all depends on that file.   If there is a range of identifiers then put them all in a list of string and work through the list in a loop - if it gets to the end of the loop without finding a match, write the line.

Answer 9

BTW, I wouldn't delete the original file before the new one has been written.

---

Armin

Answer 10

Also consider using a StringBuilder when building your new text file.

---

Please call me Frank :)

Answer 11

BTW, I wouldn't delete the original file before the new one has been written.

That would require creating the new file with a unique name then renaming it after deleting the original.  That's considerably beyond the original task.    However, if that sort of protection is required it's probably simpler to create a backup of the original before deleting it. 

Answer 12

"That's considerably beyond the original task."

Sure. Though I think it's ok to give that hint.

---

Armin