TextFiles

using System;
using System.IO;
using System.Text;
//Write a program that reads a text file and inserts line numbers in front of each of its lines.
//The result should be written to another text file.
class InsertLineNumbers
{
    static void Main()
    {
        using (StreamWriter writer = new StreamWriter("new.txt"))
        using (StreamReader reader = new StreamReader("streamreader.txt"))
        {
            StringBuilder builder = new StringBuilder();
            string line;
            int lineNum = 1;
            while ((line = reader.ReadLine()) != null)
            {
                builder.Append(lineNum).Append(". ").Append(line);
                writer.WriteLine(builder.ToString());
                builder.Clear();
                lineNum++;
            }
        }
    }
}