Using Files

Richard Brennan

Hi

Im totaly new to c#.

Q1: If i had a file like

Richard,Brennan
Jane,Smith
Paul,Grain

etc and a read each line 1 at a time, I assume that the whole line, 'Richard,Brennan' is read into the IO stream.
Whats the best way to get each name seperated into their own string?

(Right I have found split() and used it OK so ignore this one. Pls look at Q2.

Q2: How do i delete a specific line from a txt file?
And when i close the IO stream - does it save it and remove the white space?

Example, remove jane from above and close the gap.

9 Replies

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Guest User15y ago
Accepted answer
The filename is misspelled in the Delete method.
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Vulpes15y ago
If you mean that you want to remove the users' names but leave everything else in the file then, yes, the theLizard's idea would work.

If you split each line using the comma separator, you can ignore the column(s) you don't want, Trim() and recombine what's left and add it to the list for writing back to the file.
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Richard Brennan15y ago
well the file is a list a registered users for my app.
And i want to remove any user and white space.
Would the lizards idea work?
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Sam Hobbs15y ago
As theLizard says, you don't need to copy or move anything unless you need to need to copy or move something. I don't know what you need to do.

Also, it might work to simply search the data using Contains as theLizard shows but it might not work. It depends on what your requirements are.
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theLizard15y ago
This is all you need to do...

You don't need to copy or move anything...

            List myLines = new List();
            string FileName = @"C:\myFile.Text";
            StreamReader sr = new StreamReader(FileName);

                {
                    string line;
                    while ((line = sr.ReadLine()) != null)
                    {

                        if (!line.Contains("Jane"))
                            myLines.Add(line + Environment.NewLine);

                        // do whatever
                    }
                sr.Close();

                StreamWriter sw = new StreamWriter(FileName);
                for (int i = 0; i < myLines.Count; i++)
                    sw.Write(myLines[i]);
                sw.Flush();
                sw.Close();

                }
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Frogleg15y ago
To move a file with overwrite use
File.Move("temp.txt","password.txt",true);
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Sam Hobbs15y ago
That data is called Comma Separated Values (CSV). Look for articles in this web site about CSV files.

Also note that if you open and close a file then you need to do something such as delete or move the file, you might need to call Dispose() for the file object. If you get a sharing violation or if the system says it cannot access the file to do the move or delete, then probaly you need to Dispose() the file object first. Avoid calling Dispose() unless you know there is a need for it.

I am not sure, but I think that you don't need to do a Dispose() if you use a "using" statement for the file object.
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Richard Brennan15y ago
i have managed to copy the data into a temp file
but when i try to rename them using

File.Delete("pasword.txt");
File.Move("temp.txt","password.txt");

i get a run time error - can rename a file that exists - so the delete has not not worked - any ideas.

Holy do dar - spelling error lol - its sorted. What a silly billy. lol
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Guest User15y ago
Write another file with the names you want to save, then delete the 1st file and rename the new file.
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