Build a byte array[4] using individual values/variables

Question

Little bit of background first on my goal then I will show you my code and which approach I currently view as being the best approach at this moment in time.

My Goal : I have an XML file where I have 5 values stored which I want to create a byte array with these values

I have the following command hardcoded in my application using Microsoft.PointOfService :

m_Printer.PrintNormal(PrinterStation.Receipt, System.Text.ASCIIEncoding.ASCII.GetString(new byte[] { 27, 112, 48, 55, 121 }))

As you can see, the byte array is hardcoded.

This code works ok, but what I have done is created an XML file which will be read to read in the values ( these values are used to fire a cash drawer connected via a RJ11 cable to an EPSON printer ) so that the user can change the xml and not have to recompile the code.

The XML is below :

<OpenCashDrawerCommand> 
    <Byte1 value="27"/> 
    <Byte2 value="112"/> 
    <Byte3 value="48"/> 
    <Byte4 value="55"/> 
    <Byte5 value="121"/> 
</OpenCashDrawerCommand>

So you can see I am taking the hardcoded values from the C# code and reading it into 5 variables somewhere in my code.

I then want to create a byte array using these 5 values and pass the new byte array like this:

m_Printer.PrintNormal(PrinterStation.Receipt, System.Text.ASCIIEncoding.ASCII.GetString(MYNEWBYTEARRAY);

This link contains an approach which I have considered using : Converting a list of ints to a byte array

var bytes = integers.Select(i => BitConverter.GetBytes(i)).ToArray();

So, if i can take the values in my xml ( which i am already reading into a class currently ) and build a byte array, i can then just grab that byte array ( which can be static and more than likely will be for my singleton class ) then that will be job done :)

Any thoughts dudes and dudettes?

Thanks alot :)

Have you tried it? Does it do what you want? (It looks like it should). In general, questions such as "any thoughts" are going to be considered "off-topic": stackoverflow.com/faq#dontask — Michael Edenfield
– Michael Edenfield, Commented Feb 12, 2013 at 21:57
Are you set on using the "byte1", "byte2", ... naming convention? — JerKimball
– JerKimball, Commented Feb 12, 2013 at 22:04
Since you're just taking the byte array you get from the XML and doing System.Text.ASCIIEncoding.ASCII.GetString(byteArray), wouldn't it make more sense just to put the ASCII string as a field in the XML file, rather than the bytes of the characters as integers? — Timothy Shields
– Timothy Shields, Commented Feb 12, 2013 at 22:55

usr · Accepted Answer · 2013-02-12 21:59:52Z

1

Well you need to extract the values from the XML. I'll assume you can use XLINQ:

XDocument doc = XDocument.Parse(xmlString);
XElement root = from e in doc.DocumentElement/*don't remember the exact name*/;
var byteElements = new [] { root.Element("Byte1"), root.Element("Byte2"), ... };
var bytes =
 byteElements
 .Select(elem => (byte)elem); //this "cast" is an implicit conversion operator
 .ToArray();

And there you go. If I got something minor wrong you'll be able to fix it.

answered Feb 12, 2013 at 21:59

usr

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Comments

JerKimball · Accepted Answer · 2013-02-12 22:11:50Z

I would say scrap the "ByteN" naming convention and just use XML serialization to turn into/from xml:

[Serializable]
public class SomeClass
{
    // Serialize the list as an array with the form:
    //  <OpenDrawerCommand>
    //      <byte>...</byte>
    //      <byte>...</byte>
    //      <byte>...</byte>
    //  </OpenDrawerCommand>
    [System.Xml.Serialization.XmlArray("OpenDrawerCommand")]
    [System.Xml.Serialization.XmlArrayItemAttribute("byte")]
    public List<byte> CommandBytes {get; set;}
}


void Main()
{
    var cmd = new SomeClass() 
    { 
        CommandBytes = new List<byte> { 27, 112, 48, 55, 121 }
    };
    var originalBytes = cmd.CommandBytes;

    var sb = new StringBuilder();
    var ser = new System.Xml.Serialization.XmlSerializer(typeof(SomeClass));
    using(var sw = new StringWriter(sb))
    using(var xw = XmlWriter.Create(sw))
        ser.Serialize(xw, cmd);
    Console.WriteLine(sb.ToString());

    cmd = new SomeClass();
    Debug.Assert(cmd.CommandBytes == null);

    using(var sr = new StringReader(sb.ToString()))
    using(var xr = XmlReader.Create(sr))
        cmd = (SomeClass)ser.Deserialize(xr);
    Debug.Assert(cmd.CommandBytes.SequenceEqual(originalBytes));

    Console.WriteLine(string.Join(", ", cmd.CommandBytes));
}

The XML from the above looks like:

<?xml version="1.0" encoding="utf-16"?>
<SomeClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <OpenDrawerCommand>
        <byte>27</byte>
        <byte>112</byte>
        <byte>48</byte>
        <byte>55</byte>
        <byte>121</byte>
    </OpenDrawerCommand>
</SomeClass>

Thanks for your time JerKimball for looking into this question .. much appreciated :)

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