Reading Data from a Text File Using .NET

Data can be read from a text file by way of the System.IO namespace. This namespace allows the reading from and writing to files and data streams. The StreamReader class can be used to access a text file and read it line by line.

Below are the main methods in the StreamReader class.

Text File (used in the sample program)

Sample C# Program

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace ReadTextFile
{
  class ReadText
  {
    static void Main(string[] args)
    {
      //- Location of the Text file
      string fileName = @"c:temptxt_test.TXT";
      //- Set the line counter
      int lineNumber = 0;

      //- Write initial text to the console
      Console.WriteLine("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
      Console.WriteLine("MY FAVORITE SONGS");
      Console.WriteLine("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");

      //- Open the text file
      using (StreamReader sr = new StreamReader(fileName))
      {
         //- Initialize name variables
         string aName = "";
         string sName = "";
         string alName = "";
         string line;    //- Holds the entire line

         //- Cycle thru the text file 1 line at a time pulling
         //- substrings into the variables initialized above
         while ((line = sr.ReadLine()) != null)
         {
            lineNumber++;

            //- Pulling substrings.  If there is a problem
            //- with the start index and/or the length values
            //- an exception is thrown
            try
            {
               aName = line.Substring(0,21).Trim();
               sName = line.Substring(22,25).Trim();
               alName = line.Substring(47,17).Trim();
            }

            catch (Exception ex)
            {
               Console.Write(ex.ToString());
            }

            //- Write the information to the console
            Console.WriteLine("Artist: {0}", aName);
            Console.WriteLine("Title : {0}", sName);
            Console.WriteLine("Album : {0}", alName);
            Console.WriteLine("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
         }
         sr.Close();
      }
    }
  }
}

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Sample VB.NET Program

Imports System.IO
Module ReadText_vb

 Sub Main()
   ‘- Location of the Text file
   Dim fileName As String = "c:temptxt_test.TXT"
   ‘- Set the line counter
   Dim lineNumber As Integer = 0

   ‘- Write initial text to the console
   Console.WriteLine("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~")
   Console.WriteLine("MY FAVORITE SONGS")
   Console.WriteLine("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~")

   ‘- Open the text file/stream
   Dim sr As StreamReader = New StreamReader(fileName)

   ‘- Initialize name variables
   Dim aName As String = ""
   Dim sName As String = ""
   Dim alName As String = ""
   Dim line As String = ""

   ‘- Cycle thru the text file 1 line at a time pulling
   ‘- substrings into the variables initialized above
   Do
       line = sr.ReadLine()
       ‘- If it goes past the last line of the file,
       ‘- it drops out of the loop
       If line <> Nothing Then
         Try
           aName = line.Substring(0, 21).Trim()
           sName = line.Substring(22, 25).Trim()
           alName = line.Substring(47, 17).Trim()
         Catch ex As Exception
           Console.Write(ex.ToString())
         End Try

         ‘- Write the information to the console
         Console.WriteLine("Artist: {0}", aName)
         Console.WriteLine("Title : {0}", sName)
         Console.WriteLine("Album : {0}", alName)
         Console.WriteLine("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~")
        End If
   Loop Until line Is Nothing
   ‘- Close the file/stream
   sr.Close()
 End Sub

End Module

Output

Among many other classes, the System.IO namespace also contains the StreamWriter class which I will go over in a future post.

Related Links

Text Reader and Text Writer in C#

C# Input/Output Classes Simplified

Reading Text Files in an ASP.NET Web Page

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