String representation of byte array

Question

I have a string that represents a byte

string s = "\x00af";

I write this string to a file so the file contains the literal "\x00af" and not the byte it represents, later I read this string from the file, how can I now treat this string as byte again (and not the literal)?

Here is a sample code:

public static void StringAndBytes()
{
    string s = "\x00af";
    byte[] b = Encoding.ASCII.GetBytes(s);

    // Length would be 1
    Console.WriteLine(b.Length);

    // Write this to a file as literal
    StreamWriter sw = new StreamWriter("c:\\temp\\MyTry.txt");
    sw.WriteLine("\\x00af");
    sw.Close();

    // Read it from the file
    StreamReader sr = new StreamReader("c:\\temp\\MyTry.txt");
    s = sr.ReadLine();
    sr.Close();

    // Get the bytes and Length would be 6, as it treat the string as string
    // and not the byte it represents
    b = Encoding.ASCII.GetBytes(s);
    Console.WriteLine(b.Length);
}

Any idea on how I convert the string from being a text to the string representing a byte? Thx!

Don't write it like that. You don't want to have to write a C# compiler to read it back. And never store bytes in a string, not all byte values are legal Unicode characters. Use Convert.ToBase64String to encode byte[] into a string that you can easily write to a text file. — Hans Passant
– Hans Passant, Commented Mar 3, 2011 at 1:53

Fun Mun Pieng · Accepted Answer · 2011-03-03 01:46:38Z

1

Is it a requirement for the file content to have the string literal? If no, then you might want to write the byte[] b array directly to the file. That way when you read it, it is exactly, what you wrote.

byte[] b = Encoding.UTF32.GetBytes(s);
File.WriteAllBytes ("c:\\temp\\MyTry.txt", b);

b = File.ReadAllBytes ("c:\\temp\\MyTry.txt");
s = Encoding.UTF32.GetString (b);

If you need the file content to have the string literal, while being able to convert it to the original text written, you will have to choose the right encoding. I believe UTF32 to be the best.

    b = new byte[4];
    b[0] = Byte.Parse(s.Substring(2), System.Globalization.NumberStyles.AllowHexSpecifier);
    string v = Encoding.UTF32.GetString(b);
    string w = "\x00af";

    if (v != w)
        MessageBox.Show("Diff [" + w + "] = [" + v + "] ");
    else
        MessageBox.Show("Same");

answered Mar 3, 2011 at 1:46

Fun Mun Pieng

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1 Comment

ValYouW Over a year ago

Thank you! your second example was exactly what I wanted. The file have to have the literal (what Im doing actually is parsing .cs files looking for those special strings and manipulate them).

MartinStettner · Accepted Answer · 2011-03-03 01:36:15Z

1

Not sure if I understand the question correctly, but you're not writing the string s to the file. You have an extra \ in your WriteLine statement! WriteLine("\\x00af") writes the characters \, x, 0, 0, a and f, since the first \ acts as an escape to the second one ...

Did you mean

sw.WriteLine("\x00af");

or

sw.WriteLine(s);

instead? This works as expected in my tests.

edited Mar 3, 2011 at 1:36

answered Mar 3, 2011 at 1:30

MartinStettner

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PedroC88 · Accepted Answer · 2011-03-03 01:26:15Z

0

Use the Encoding.ASCII.GetString(byte[]) method. It is also available from all the others encoding. Make sure you always use the same encoding to decode the byte[] as you used to encode it or you won't get the same value every time.

Here's an example.

answered Mar 3, 2011 at 1:26

PedroC88

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Paul · Accepted Answer · 2011-03-03 01:29:54Z

0

Just parse a string representing each byte:

Byte b = Byte.Parse(s);

answered Mar 3, 2011 at 1:29

Paul

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1 Comment

Hans Passant Over a year ago

Yes, but doesn't parse "\x00af".

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