Replace a word from a specific line in a text file

Question

I\'m working on a little test program to experiment with text files and storing some data in them, and I\'ve stumbled accross a problem when trying to replace a value in a s

Answer 1

Try this:

var path = @"c:\temp\test.txt";
var originalLines = File.ReadAllLines(path);

var updatedLines = new List<string>();
foreach (var line in originalLines)
{
    string[] infos = line.Split(',');
    if (infos[0] == "user2")
    {
        // update value
        infos[1] = (int.Parse(infos[1]) + 1).ToString();
    }

    updatedLines.Add(string.Join(",", infos));
}

File.WriteAllLines(path, updatedLines);

Answer 2

use ReadLines and LINQ:

var line = File.ReadLines("path")
               .FirstOrDefault(x => x.StartsWith(username));

if (line != null)
{
     var parts = line.Split(',');
     parts[1] = "1500"; // new number
     line = string.Join(",", parts);
     File.WriteAllLines("path", File.ReadLines("path")
         .Where(x => !x.StartsWith(username)).Concat(new[] {line});
}