but I really need to do the job. What if I used a rich text box? Will I be able to do as I said? 

I am trying to write a code in windows forms in c# to open two text files and compare them. 

the process is as follows:

1- two text boxes are provided on the window

2- the files are loaded into text boxes using OpenFileDialogue 

3- I want to have the first text as the base and compare the second one to that and highlight the similarities and differences using different colors on the second text.

I actually don't know how to do step 3.

many thanks for your helps!!

thanks a lot

best regards!

I myself tried the following code to do the job, but your code is far more simple and better:

using System;
using System.IO;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            StreamReader myreader = new StreamReader(@"D:\ekhtera\textFile.txt");
            string[] array = new string [arrayDimension(myreader)];
            StreamReader reader = new StreamReader(@"D:\ekhtera\textFile.txt");
            string line = "";
            int index = 0;
            while (line != null)
            {
                line = reader.ReadLine();
                if (line != null)
                    array[index] = line;
                index++;
            }
            Console.WriteLine(array[4]);
            reader.Close();
            Console.ReadKey();

        }

        private static int arrayDimension(StreamReader newStream)
        {
            string line = "";
            int i = 0;
            while (line != null)
            {
                line = newStream.ReadLine();
                if (line != null)
                    i++;
            }
            newStream.Close();
            return i;
        }
    }
}

thanks, but I have already tried that. 

no satisfactory results!!!

I have spent hours in MDSN and I couldn't find any efficient method for communicating with USB using C#.

I want to create an application to select an MP3 and send it to the circuit I have designed and connected to USB (AM modulator), and then receive and play it with a regular radio. so I need to define the USB to C# and I don't know how to do it.

regards

this is not a homework assignment. it's not even a part of that too.

it is a very small part of a big robotic project that is under development. in order to program a micro-controller I need to convert all these numbers every time and I thought it would be nice if I have the application on my computer. The one I create myself. I have worked with C and java. I'm just not so familiar with C#. but I think I like this language.

and two minutes after I posted this question, I found the answer for my first question. I can change it in the property window of TextBox (MaxLength property). And some of you mentioned this.

anyway, thanks for your time and answers

I'm having a problem with a program I'm trying to write in windows forms. I want to write a program to convert binary numbers (1Byte) to hexadecimal.

the program works like this:

user inserts a binary number in a textbox and the result will be shown in another textbox.

I know the algorithm and everything. there is just one problem:

since the number must be binary I don't want the keyboard type in any other numbers ( other than 0 and 1) or other characters. I want to disable them in my application. how can I do that?

best regard