I am working on a program with a list box that displays text from a selected text file. I have already made it to delete the item from the listbox but I don't know how to get it to delete that same line from the text file so it doesn't just display it again when you reopen the dialog. Any help? I am using streamwriter and streamreader. I can also TeamView if needed.
The easiest and in most cases best approach is to overwrite the whole file. So you you want to delete all lines that are no longer in the ListBox?
Dim resultLines = From line In IO.File.ReadAllLines(path)
Join item In lb.Items On item.ToString Equals line
Select line
IO.File.WriteAllLines(path, resultLines)
This reads all lines from the file and joins them with the not deleted items in the ListBox. The resulting lines are written back to the file.
The simplest method is to re-write the file using the contents of the listbox. You didn't specify any mapping from the text file to the listbox, so I can't give more detail.
Related
I need to append 1 text file to another text file.
I've done several keyword searches, and keep coming up with instructions on adding text to an existing file ... which is not the same as appending one text file to another text file.
In a well-designed language, it might look something like the line below, with the contents of source2 added to source1.
Append(path/source1, path/source2, ResultCode)
This might be something that I am overlooking, as I am currently reading a book on VB.NET. I canceled a course in VB.Net recently because I was stuck on a problem and the lecturer did not get back to me with my questions that I had.
The objective was to create a business application with VB.NET that writes data from text boxes to a text file, seperated by a comma or a pipe. The user of the application must be able to select the directory where they want the file to be saved.
So I have for example 2 forms, one that captures the data for a client, and another form where you can select from a drop-down control, Now I know that streamwriter allows for the user to select self where they want the file to be saved, but how do I make the second form intelligent to know where the user saved the form and then reads the client_id, and fills the other data associated with the client_id to the text boxes in the form. I know streamreader is the one to use when you want to read data from a file, but how will streamreader know where the user will save the file to?
I am not doing the course any more, but I will keep on thinking what I could have done to actually get the project to work.
For writing to file
// Write single line to new file.
Using writer As New StreamWriter("C:\log.txt", True)
writer.WriteLine("Important data line 1")
End Using
For reading from file
// read from a file
Dim line As String
Using reader As New StreamReader("file.txt")
line = reader.ReadLine()
End Using
Console.WriteLine(line)
I have created a text file named 'Notes' in the resources of my project and want to load/save the text of a RichTextBox to it. I tried using MyProject.My.Resources.Notes in the path. It doesn't show any error in the code window but when I run it, it shows an error.
Here's what I'm using to load the text:
RichTextBox1.Text = System.IO.File.ReadAllText(MyProject.My.Resources.Notes)
Here's what I'm using for saving it:
System.IO.File.WriteAllText(MyProject.My.Resources.Notes, RichTextBox1.Text)
This is not a duplicate. I did not get an answer from the other question
Why don't you use a regular file which always works fine or a database?
Edit: maybe this helps?
www.dondraper.com/2011/01/easily-save-and-retrieve-application-and-user-settings-in-vb-net-or-c-apps/
How can I append text to the end a line in a text file with lines already there in VB.NET?
For example my text file looks like this:
header1,header2,header3
value1,value2,value3
stuff1,stuff2,stuff3
and I want to add new text to the end of each line so it looks like this:
header1,header2,header3,newheader
value1,value2,value3,newvalue
stuff1,stuff2,stuff3,newstuff
I know that in Perl you can point to the line and then act on it, is there some VB.net way to do this?
If the file isn't too big, the simplest is, probably, to use the IO.File.ReadAllLines method to read the file into memory and modify the data and write it back with the WriteAllLines method.
For very large files you're probably looking at reading each line modifying it and writing it to a different file.
I have a large file which i am writing to a smaller file in VB, i just dont know how to select lines from an input file that i opened.
I would like to keep the first 12 lines of the large file and them copy every 3rd line into the new output.
Any help?!
You can do this with a StreamReader - just open one on the file, then you can call ReadLine() on it as many times as you need.
Easiest implementation would probably be a 0-to-11 (or 1-to-12) For loop, then a While where you read 2 and ignore them, then read the 3rd and write it.
Writing the new file can be done with StreamWriter, which just has a WriteLine() method to write the text.
The StreamReader and StreamWriter are generally the easiest ways to read and write text files.