Create a .txt file if doesn't exist, and if it does append a new line

Question

I would like to create a .txt file and write to it, and if the file already exists I just want to append some more lines:

string path = @\"E:\\AppServ\\Examp         


        

Answer 1

string path = @"E:\AppServ\Example.txt";
File.AppendAllLines(path, new [] { "The very first line!" });

See also File.AppendAllText(). AppendAllLines will add a newline to each line without having to put it there yourself.

Both methods will create the file if it doesn't exist so you don't have to.

• File.AppendAllText
• File.AppendAllLines

Answer 2

You could use a FileStream. This does all the work for you.

http://www.csharp-examples.net/filestream-open-file/

Answer 3

File.AppendAllText adds a string to a file. It also creates a text file if the file does not exist. If you don't need to read content, it's very efficient. The use case is logging.

File.AppendAllText("C:\\log.txt", "hello world\n");

Answer 4

 else if (File.Exists(path)) 
{ 
  using (StreamWriter w = File.AppendText(path))
        {
            w.WriteLine("The next line!"); 
            w.Close();
        }
 } 

Answer 5

You don't actually have to check if the file exists, as StreamWriter will do that for you. If you open it in append-mode, the file will be created if it does not exists, then you will always append and never over write. So your initial check is redundant.

TextWriter tw = new StreamWriter(path, true);
tw.WriteLine("The next line!");
tw.Close(); 

Answer 6

When you start StreamWriter it's override the text was there before. You can use append property like so:

TextWriter t = new StreamWriter(path, true);