Foreach Loop File.Readlines displays nothing

Question

I have a foreach loop that is supposed to display lines from a txt file when I click a button. Nothing is displaying when I click the button. What am I doing wrong?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;

namespace WebApplication1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Main(object sender, EventArgs e)
        {
            foreach (string line in File.ReadLines(@"C:\Users\Matt\Desktop\AirportCodes2.txt"))
            {
                if (line.Contains("Chicago"))
                {
                    Console.WriteLine(line);
                }
            }
        }
    }
}

Text file is tab delimited, formatted like this:

Chicago IL ORD O'Hare International

Console.WriteLine in a web form? Does it work in a console app? — Austin Salonen, Mar 13 '13 at 19:38
I am attempting to do this in a web form. Is there a simple way to do this? I am struggling to find documentation online. — rupes0610, Mar 13 '13 at 19:39
Also, nowhere in there is a button click handler defined. WebForms don't do `Main`. You got some readin' to do. — Sam Axe, Mar 13 '13 at 19:40
`Console.WriteLine` is going to write a line to the console; not the page response. That's what the "Console" part means. — Dan, Mar 13 '13 at 19:41
Change "Main" to "Page_Load" and "Console.WriteLine" to "Response.Write" and you should see something. But you do need to do a bit of research :) — Stephen Byrne, Mar 13 '13 at 19:41
You're approaching this in an extremely wrong way. You are missing many basic concepts in web applications. I would suggest you drop everything, and find a good ASP.NET tutorial. — System Down, Mar 13 '13 at 19:42

Sunny · Accepted Answer · 2013-03-13T21:13:47.823

Since it is web form, hook up Page_Load event of the page. But I recommend to go through ASP.NET page life cycle to understand pre-defined events.

 protected void Page_Load(object sender, EventArgs e)
 {
     foreach (string line in File.ReadLines(@"C:\Users\Matt\Desktop\AirportCodes2.txt"))
     {
         if (line.Contains("Chicago"))
         {
                 Response.Write(line);
         }
     }
}

Since it is web application, place the txt file in App_Data folder and access it using Server.MapPath function. Reason being that the path might be different from the local machine and when you finally deploy it to web server.

Import using System.Text; namespace

 StringBuilder result = new StringBuilder();
 int i = 0;
 foreach (string line in File.ReadLines(Server.MapPath("~/App_Data/AirportCodes2.txt")))
 {
       if (line.Contains("Chicago"))
       { 
           i = i + 1;
           result.Append((string.Format("label{0}:{1}",i,line));
           result.Append("<br/>");
       }
}
lblAirportCodes = result.ToString();

In aspx:

<asp:Label runat="server" id="lblAirportCodes"/>

would there be a way to dynamically add the lines to a label? Label{1}.(line) instead of Response.Write(line);? — rupes0610, Mar 13 '13 at 20:06
that will add label1:Chicago IL ORD O'Hare International I meant existing WebControl Labels. I appreciate your help. — rupes0610, Mar 13 '13 at 20:21

Foreach Loop File.Readlines displays nothing

1 Answers1