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

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});
}