Question

I am making a project that uses streamreader and streamwriter, Is it possible that I only replace or save a text in an specific line only without affecting the other lines?
if I make like this

streamreader sr = new streamreader(@"txtfile");
list<string> lines = new list<string>();
while (!sr.EndOfStream)
sr.readline();
{
     lines.Add(sr.ReadLine();
}

//put in textbox
sr.close();

{
streamwriter sw = new streamwriter(@"txtfile");
sw.WriteLine(textBox1.text);
sw.close();
}

this is just a sample, but Is it possible that I use list also un streamwriter?

Answer 1

You cannot just change a line as such but you can to ReadAllLines, find the line you want to change, change it and write all of it to the file again :

StringBuilder newFile = new StringBuilder();
string temp = "";
string[] file = File.ReadAllLines(@"txtfile");

foreach (string line in file)
{
    if (line.Contains("string you want to replace"))
    {
        temp = line.Replace("string you want to replace", "New String");
        newFile.Append(temp + "\r\n");
        continue;
    }
    newFile.Append(line + "\r\n");
}

File.WriteAllText(@"txtfile", newFile.ToString());