Why am I not getting the actual string value with this byte array conversion?

Question

I am trying to send a "getvar" command to a printer over the serial port, and receive the response, but all I'm getting when trying to verify what I'm sending, and what is received is: "System.Byte[]"

Here is my code:

const string quote = "\"";
. . .
string getDeviceLang = string.Format("! U1 getvar {0}device.languages{0}", quote);
. . .
String deviceLanguage = PrintUtils.GetSettingFromPrinter(getDeviceLang);
. . .
MessageBox.Show(deviceLanguage); // <= this shows "System.Byte[]"

public static string GetSettingFromPrinter(string cmd)
{
    string setting = string.Empty;
    try
    {
        BasicPortSettings bps = new BasicPortSettings();
        bps.BaudRate = BaudRates.CBR_19200;
        bps.Parity = OpenNETCF.IO.Serial.Parity.none;
        bps.StopBits = OpenNETCF.IO.Serial.StopBits.one; 

        Port serialPort = new Port("COM1:", bps);
        serialPort.Open();
        byte[] outputBytes = Encoding.ASCII.GetBytes(cmd);
        MessageBox.Show(Convert.ToString(outputBytes)); // <= this shows "System.Byte[]"
        serialPort.Output = outputBytes;
        byte[] inputBytes = serialPort.Input;
        setting = Convert.ToString(inputBytes);

        serialPort.Close();
        return setting;
    }
    catch (Exception x)
    {
        MessageBox.Show(x.ToString());
        return setting;
    }
}

What do I need to do to actually see the string I'm passing and receiving, rather than just a string representation of the data type?

UPDATE

Does this look right:

setting = System.Text.Encoding.ASCII.GetString(
    inputBytes, 0, inputBytes.Length);

? It at least compiles, but...

UPDATE 2

Okay, this code:

public static string GetSettingFromPrinter(string cmd)
{
    string setting = string.Empty;
    try
    {
        BasicPortSettings bps = new BasicPortSettings();
        bps.BaudRate = BaudRates.CBR_19200;
        bps.Parity = OpenNETCF.IO.Serial.Parity.none;
        bps.StopBits = OpenNETCF.IO.Serial.StopBits.one; 

        Port serialPort = new Port("COM1:", bps);
        serialPort.Open();
        byte[] sendBytes = Encoding.ASCII.GetBytes(cmd);
        MessageBox.Show(Encoding.ASCII.GetString(sendBytes, 0, 
                        sendBytes.Length));
        serialPort.Output = sendBytes;
        byte[] receiveBytes = serialPort.Input;
        setting = GetString(receiveBytes);
        serialPort.Close();
        return setting;
            }
    catch (Exception x)
    {
    MessageBox.Show(x.ToString());
    return setting;
    }
}

...does return the expected val (! U1 getvar "device.language") here:

MessageBox.Show(Encoding.ASCII.GetString(sendBytes, 0, sendBytes.Length));

...but still an empty string here:

        String deviceLanguage = PrintUtils.GetSettingFromPrinter(getDeviceLang);
        MessageBox.Show(deviceLanguage);

// Helper function, from http://stackoverflow.com/questions/472906/converting-a-string-to-byte-array
static string GetString(byte[] bytes)
{
    char[] chars = new char[bytes.Length / 2];
    System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
    return new string(chars);
}

Maybe the "sendBytes" simply aren't being sent, and that's why there's no response/nothing in receiveBytes...

have you tried just sending `cmd`? Plain text instead of bytes? — ps2goat, Jun 11 '14 at 19:28
Basically, `Convert.ToString()` isn't what you want for binary to text conversion - you want `Encoding.GetString`. — Jon Skeet, Jun 11 '14 at 19:28
If you haven't read this yet, do so before you write any more code that deals with strings: http://www.joelonsoftware.com/articles/Unicode.html — Eric Lippert, Jun 11 '14 at 19:36
@ps2goat: Sure, I tried that, but the Output property expects a byte array. — B. Clay Shannon-B. Crow Raven, Jun 11 '14 at 20:28

score 2 · Accepted Answer · answered Jun 11 '14 at 19:30

If you want to see the bytes in hex form, just use BitConverter.ToString(byte[]). That will give you output such as "01-56-AF".

If you want the text - well, you've got that already as cmd - but in general, to convert a byte[] to the text that it represents, use Encoding.GetString(bytes) using a suitable encoding.

Fundamentally, there's no "actual string value" for a byte array - there are many different ways of converting an arbitrary array of bytes into text, and you need to pick the right approach for your context.

score 1 · Answer 2 · answered Jun 11 '14 at 19:30

1

Change

setting = Convert.ToString(inputBytes);

to

setting = System.Text.Encoding.ASCII.GetString(inputBytes);

answered Jun 11 '14 at 19:30

David Crowell

3,711
21
28

I get, "No overload for method 'GetString' takes '1' arguments" – B. Clay Shannon-B. Crow Raven Jun 11 '14 at 20:30
1

@B.ClayShannon, Odd. It compiles fine on my machine. – David Crowell Jun 12 '14 at 11:17
Probably because I'm using a prehistoric version of everything. – B. Clay Shannon-B. Crow Raven Jun 13 '14 at 15:23
1

That's valid all the way back to .NET 2.0. Aren't earlier versions unsupported now? – David Crowell Jun 13 '14 at 16:24
1

Everything we use (only slight exaggeration) is unsupported, including the hardware our users use (ancient version of handheld device, belt printer, etc.) Pterodactyls still roamed the skies when this stuff was in vogue. – B. Clay Shannon-B. Crow Raven Jun 13 '14 at 17:41

Why am I not getting the actual string value with this byte array conversion?

UPDATE

UPDATE 2

2 Answers2