asked on

Reading bytes from a text file using "StreamReader.BaseStream".

Hi, I’m using MS VS 2010 C#.NET, I’m trying to read a file from disk and send the BaseStream to a textbox on one of my Forms. Below is my code. It's working, but it’s doing so very, very slowly. A 16KB file took about 15 minutes to read and send to the textbox. A 10 KB file took close to 4 minutes to process. I’m sure I’m doing something wrong and I’m sure there’s a much more efficient manner to do so.

If you'd like to create the Form, its simply a Button named "btnRead" and multiline Textbox named "tbxText", with a vertical scroll-bar and its Font set to Courier New." You can use any text file you'd like for testing.

Can anyone help me to increase the efficiency of this code?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace Reader
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        // Checks for file. If it exists, it reads it.
        private void btnRead_Click(object sender, EventArgs e)
        {
            string path = @"C:\TestData\testfile.txt";
            string fileLength = "";
            string strBuffer = "";
            
     Console.WriteLine("Started at : " + DateTime.Now);
            if (File.Exists(path))
            {
                Console.WriteLine("The file exists");
                StreamReader sr = new StreamReader(File.OpenRead (path));
                fileLength =  sr.BaseStream.Length.ToString();
                Console.WriteLine(fileLength);

                byte[] buffer = new byte[(long)sr.BaseStream.Length];
                sr.BaseStream.Position = 0;
                sr.BaseStream.Read(buffer, 0, ((int)sr.BaseStream.Length));
                int i = 0;
                foreach ( byte myByte in buffer)
                {
                   
                    strBuffer += myByte.ToString("X2") + " ";
                    tbxText.Text = strBuffer;
                    i++;
                }
                               
                sr.Dispose();
            }
            else
            {
                Console.WriteLine("The file does NOT exists");
            }
            Console.WriteLine("Ended at : " + DateTime.Now);
            Console.WriteLine("Stop...");


        }
        
    }
}

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Thanks,
Fulano

mwochnick

why read it a byte at a time your self
try something like this

// Read the file as one string.
System.IO.StreamReader myFile =
   new System.IO.StreamReader("c:\\test.txt");
string myString = myFile.ReadToEnd();

myFile.Close();

// Display the file contents.
Console.WriteLine(myString);
// Suspend the screen.
Console.ReadLine();

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In your case assign myString to the textbox.Text

Cong Minh Vo

it’s doing so very, very slowly because this code:

 foreach ( byte myByte in buffer)
                {
                   
                    strBuffer += myByte.ToString("X2") + " ";
                    tbxText.Text = strBuffer;
                    i++;
                }

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you can change to:

foreach ( byte myByte in buffer)
                {
                   
                    strBuffer += myByte.ToString("X2") + " ";
                  
                    i++;
                }
  tbxText.Text = strBuffer;

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ASKER CERTIFIED SOLUTION

Mike Tomlinson

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Mr_Fulano

ASKER

Wow...all very good suggestion. I tried Idle_Mind's first suggestion and was able to read a 704KB file in 3 seconds...now that's what I was looking for!!!

Idle_Mind, you offered two options....why would one be better that the other or why would I not want to use the ReadAllBytes() method?

Thanks for all your help!
Fulano

Mr_Fulano

ASKER

Hi Minhve, I tried your suggestion, but it still took long...several minutes.

Thanks,
Fulano

Mr_Fulano

ASKER

Hi Mwochnick, I also tried your suggestion, but it failed to give me the results I was expecting. Thanks for your help.

Fulano

Mike Tomlinson

You wouldn't want to use ReadAllBytes() with a LARGE file as it reads the entire file at once and returns a byte[] array. This may take a long time and use a lot of memory.

For large files, you'd want to use the second approach that only reads a byte at a time.

Mr_Fulano

ASKER

OK, thanks....one last question. I would also need a method that allows me to jump around the file. The StreamReader.BaseStream method allowed me a Position property. So, I was able to jump to byte number 208, if I had the need to do so.

How would I do that with your options?

Thanks,
Fulano

Kumaraswamy R

Hi

Try

http://www.dotnetfunda.com/articles/article462-different-ways-of-reading-and-writing-text-file-data-in-net.aspx

http://www.example-code.com/vbdotnet/readFileIntoByteArray.asp

Mr_Fulano

ASKER

Hi Idle_Mind, when you say:

You wouldn't want to use ReadAllBytes() with a LARGE file

what do you mean? What constitutes a large file (i.e. 1MB, 5MB, 20MB, 1GB, etc)?

Thanks,
Fulano

Mike Tomlinson

That really depends on the system on which the program is running. A computer with tons of RAM and speed might do fine with a "large" file, while a smaller and slower system may fail or simply take much longer if it has to use the swap file on the hard drive for more memory. The second approach may take a little longer but it will use only a tiny amount of memory.

Mr_Fulano

ASKER

Mike Tomlinson

In the first option, you'd store the byte array before the foreach loop and then simply start at the correct index instead of at 0 (zero):

                byte[] bytes = System.IO.File.ReadAllBytes(fi.FullName);
                for (int i = 207; i < bytes.Length; i++)
                {
                    Buffer.Append(bytes[i].ToString("X2") + " ");
                }
                tbxText.Text = Buffer.ToString();

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For the second option, you should be able to use BaseStream.Seek():

                using (BinaryReader br = new BinaryReader(fi.OpenRead()))
                {
                    br.BaseStream.Seek(207, SeekOrigin.Begin);
                    while (br.PeekChar() != -1)
                    {
                        Buffer.Append(br.ReadByte().ToString("X2") + " ");
                    }
                }
                tbxText.Text = Buffer.ToString();

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Mr_Fulano

ASKER

Very cool code Idle_Mind...very cool indeed!

Thanks again,
Fulano

Mr_Fulano

ASKER

Excellent code! Excellent explanation. Excellent help. Thank you very much.

Reading bytes from a text file using &quot;StreamReader.BaseStream&quot;.

Reading bytes from a text file using "StreamReader.BaseStream".