C # how to update a file (keep old data)

Question

Now I write to a file:

TextWriter tw = new StreamWriter(@"D:/duom.txt");
tw.WriteLine("Text1");

When I write a second time, all data is deleted and new is written.

How do I update my data? Leave the old data and add new ones

+2

lolalola May 18 '10 at 11:37

6 answers

Use FileMode.Append

using (FileStream fs = new FileStream(fullUrl, FileMode.Append, FileAccess.Write))
{
  using (StreamWriter sw = new StreamWriter(fs))
  {

  }
}

+1

CRice May 18 '10 at 11:41 PM

You need to use an overload constructor with an add flag, and don't forget to make sure your stream is closed, complete:

using (TextWriter tw = new StreamWriter(@"D:\duom.txt", true))
{
    tw.WriteLine("Text1");
}

+1

Joel coehoorn May 18 '10 at 11:43

You must specify the FileMode . You can use:

var tw = File.Open(@"D:\duom.txt", FileMode.Append);
tw.WriteLine("Text1");

0

Reed copsey May 18 '10 at 11:41 PM

TextWriter tw = new StreamWriter(@"D:/duom.txt", true);

Will be added to the file instead of writing it

0

JHurrah May 18 '10 at 11:44 PM

You can use File.AppendText like this:

TextWriter tw = File.AppendText(@"D:/duom.txt");
tw.WriteLine("Text1");
tw.Close();

0

Joe axon May 18 '10 at 23:51

Mitch wheat · Accepted Answer · 2010-05-18T23:40:25+0000

One way is to specify true

for a flag Append

(in one of the constructor overloads StreamWriter

):

TextWriter tw = new StreamWriter(@"D:/duom.txt", true);

Note. Don't forget to wrap the operator using

.