file to read and write.

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How can I write a program to read a file of size 4096 and I have to give block code for that. After that to write the file by retrieving those block code?

My current code is this

C#

using System;
using System.IO;
class FileRead
{
    string filereadbuf;  
    public void ReadFile(string FileName, int FileSize)
    {
        char[] buf = new char[FileSize];  
        
        StreamReader sr = new StreamReader(new FileStream(FileName, FileMode.Open, FileAccess.Read));
        int retval = sr.ReadBlock(buf, 0, FileSize); // 
        Console.Write("Total Bytes Read = " + retval + "\n");
        filereadbuf = new string(buf);  
        Console.WriteLine(filereadbuf); 
        sr.Close();
    }
}

class TestFileRead
{
    public static void Main(string[] args)
    {
        String[] cmdline = Environment.GetCommandLineArgs(); 
        Console.WriteLine("File Reader Using Stream Reader & File Stream \n");
        if (cmdline.Length < 2) 
        {
            Console.WriteLine("Usage: " + cmdline[0] + " <input file> ");
            return;
        }
      
      
        File[] fe = (new Directory(".")).GetFiles(cmdline[1]);
        if (fe.Length == 0)
        {
            Console.WriteLine(cmdline[1] + ": file not found"); 
            return;
        }
        FileRead fr = new FileRead();
        try
        {
            fr.ReadFile(cmdline[1], (int)fe[0].Length); 
        }
        catch (IOException e)
        {
            Console.WriteLine("I/O error occured" + e);
            return;
        }
    } 
}

Posted 17-Jan-13 20:40pm

prajwal rao

Updated 17-Jan-13 21:09pm

lukeer

v2

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Comments

dan!sh 18-Jan-13 2:45am

Have tried something?

Andreas Gieriet 18-Jan-13 2:51am

Do you mean:
1) read 4096 bytes of data from a file
2) "decode" the block code to correct potential data errors and retrieve the payload from the file
3) store the extracted payload to a file
Is it that what you need to do?
Andi

prajwal rao 18-Jan-13 2:54am

ya you a right sir....

Andreas Gieriet 18-Jan-13 3:22am

What you show in your code has nothing to do with Block Code. So, what you you really want to achieve? From your wording, I understand that you get 4096 bytes of block encoded data and you need to store the payload into a new file. But I'm not quite sure about your wording.Please check the above mentioned link and make a clear statement if you talk about Block Code with respect to coding theory (and not as you show in your code where you read data chunk (block) wise.
Andi

prajwal rao 18-Jan-13 4:54am

sir i want to achieve as you mentioned in your first comment....
and that code which is shown only to read a file.....

Andreas Gieriet 18-Jan-13 5:27am

I assume you should work on byte[] - not on char (this is different to C/C++ world).
E.g.

static byte[] ReadFile(string path)
{
    try 
    {
        return File.ReadAllBytes(path);
    }
    catch (Exception)
    {
        return new byte[] { };
    }
}

Cheers
Andi

prajwal rao 18-Jan-13 5:32am

but how can i make a block 4096.. and how can i name them...???

Andreas Gieriet 18-Jan-13 5:56am

Did you read the link I suggested above and in my solution #1 below?
Do you know what block code is?
If not, you must first learn that before going on to implement it.
Andi

prajwal rao 18-Jan-13 6:05am

ok sir but can you tell me how to read a file of 4096 bits...

Andreas Gieriet 18-Jan-13 6:26am

Is it bits or bytes?
If the flie contains ony the 4096 [whatever units] of data and nothing else, you can read the whole file at once. That's how I understand your statement in your quesiton: [...]read a file of size 4096[...]

If it is 4069 bits, that is 4096/8 bytes (= 512 bytes = 2^9 bytes), correct?
Andi
PS: Did you see my solution #1 and #2?

prajwal rao 18-Jan-13 6:31am

ya sir i contains 4096 bits
so when we divide by 8..... its 512 bytes.....
so it contains 8 blocks of 512 bytes.....

Andreas Gieriet 18-Jan-13 6:38am

Sorry, you give weird statements. Looking at your other posts indicates that this is far beyond your current skills. Learn the very basics first. Take one of the many C# online tutorials and learn what a variable is, how to check if a file exists, how to access the command line arguments, etc.
I have to give up here since I see no chance to get you understand what Block Code means when you don't know to express unambiguously what the difference between bit and byte is.
You can not ask to assist you building a house when you do not know the meaning of the word dor, window, roof, etc. Sorry.
Andi
PS: An *please* learn to also *answer* questions. I did ask you many question above to try to clarify what you know and what you want to achieve and you only answer half of it at best. E.g. I provided code in solution #2 but you do not say it's what you need or what is missing... Difficult.
PPS: Someone else please take over.

prajwal rao 18-Jan-13 6:47am

ok...:(

lukeer 18-Jan-13 3:12am

Please use the "Improve question" link just below your question to provide such additional information. This time, I did it for you.
Please remove the code from your comment now. It is much more readable between <pre lang="c#">such tags as these</pre> in the question area.

prajwal rao 18-Jan-13 3:14am

ok sorry....

Andreas Gieriet 18-Jan-13 5:41am

What is your block code? How many bits are added and in what way?
You must provide more data to this.
Andi

prajwal rao 18-Jan-13 5:48am

ok there is a file...... it contains so many bits of data....
1)i have to read that file
2)now i have to create each block of 4096....and then i have to give code for those blocks
3) again i have to read those block...

prajwal rao 18-Jan-13 5:50am

never mind leave that point number 3..... help me to do till point number 2....please....

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Andreas Gieriet · Answer 1 · 2013-01-17T20:45:00

Solution 1

You may have a look at MSDN: Basic File I/O[^]. It provides several common scenarios and how to implement them by means of C#.

For Block Code, you find plenty of google hits, e.g. http://www.complextoreal.com/chapters/block.pdf[^].

Cheers
Andi

Posted 17-Jan-13 20:45pm

Andreas Gieriet

Updated 17-Jan-13 20:48pm

v2

Andreas Gieriet · Answer 2 · 2013-01-17T23:54:00

Your task is to implement the byte[] BlockDecode(byte[] encoded) function.
A starting point might be the following skeleton.
Since you do not provide any information so far on the block code, I can not provide any implementation for it... (see BlockDecode method body below).

C#

static void Main(string[] args)
{
   ...
   string inFilePath = ...;
   string outFilePath = ...;
   ...
   byte[] encoded = File.ReadAllBytes(inFilePath);
   byte[] decoded = BlockDecode(encoded);
   File.WriteAllBytes(outFilePath, decoded);
}
private static byte[] BlockDecode(byte[] encoded)
{
   byte[] decoded = new byte[encoded.Length];
   int decodedBytes = 0;
   // here you must provide the code for extracting the payload
   // from the encoded bytes counting up the number of decoded bytes
   ...
   Array.Resize(ref decoded, decodedBytes);
   return decoded;
}