using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(whatIWant("start_", "_end", "start_Hello World!_end\r\n"));

        Console.WriteLine(whatIWant("start_", "_end\r\n", "start_Hello World!_end\r\n"));

        //String line = sr.ReadToEnd();

        //line to get all the text from my file

        //string whatIWant = stringEditor("beginning", "end", line);

    }

​

​

    static string whatIWant(string first, string second, string whatToParse)

    {

        return whatToParse.Substring(first.Length, whatToParse.Length - first.Length - second.Length);

    } 

}