Best method to parse byte array with required chars only c#

Question

I am trying to read a message from serialport. I am reading it as bytes of data. I have a byte array which holding all the data bytes i read from serial port. My byte array holds a message string like this after converting into string.

\u0006\u0001\0d\o?\"\0$?##STA\r\nSystemLevel:Run\r\nstatus:1\r\nSensor Value:12.45\r\n................\r\nSTOP##

I look for certain byte pattern (for example start byte)from byte array once it matches converting everything to char string from that point of index to certain index length. since i know the length of the message i want convert. for example byte[25] to byte[185].

I just want to know which is the best way to read result values from the message string?? result values for example byte[28] to byte[32],byte[42] to byte[49]...etc.

Is it better to convert all required bytes to string and parse it?? or is it better to use several byte patterns to get the characters. which is the best method.

Convert it to a string first and then parse the string. This will help to avoid char encoding issues. Otherwise you might have problems with characters that are encoded into multiple bytes (using UTF8 or whatever). — Matthew Watson, Jan 08 '20 at 10:35
@MatthewWatson ok thanks for your suggestion will keep in mind. — PRV, Jan 08 '20 at 10:58

score 0 · Accepted Answer · edited Jan 08 '20 at 10:41

Here is a sample of my code that I used in a project where receiveMessage is a byte[] :

year = receiveMessage[4];
month = receiveMessage[5];
day = receiveMessage[6];
hour = receiveMessage[7];
minute = receiveMessage[8];
second = receiveMessage[9];
date = new DateTime(2000 + year, month, day, hour, minute, second);

WriteDBMessageLocation locationMessage = new WriteDBMessageLocation();
locationMessage.message = DATABASE_MESSAGE_TYPE.LOCATION;

locationMessage.trackTime = date;
locationMessage.currTime = DateTime.Now;

locationMessage.lattitude = new byte[4];
Array.Copy(receiveMessage, 11, locationMessage.lattitude, 0, 4);

locationMessage.longitude = new byte[4];
Array.Copy(receiveMessage, 15, locationMessage.longitude, 0, 4);
locationMessage.speed = receiveMessage[19];

locationMessage.courseStatus = new byte[2];
Array.Copy(receiveMessage, 20, locationMessage.courseStatus, 0, 2);

locationMessage.IMEI = byteState.Value.IMEI;
WriteDBAsync.ReadWriteFifo(WriteDBAsync.Mode.WRITE, locationMessage);```

it is better to copy only certain bytes and convert those to text. thank you. — PRV, Jan 08 '20 at 10:34

score 0 · Answer 2 · answered Jan 08 '20 at 10:45

You can always do something with for loop, like this:

using System;
using System.Text;

namespace _ {
  class Q {
    public static void Main(string[] args) {
      string str = @"\u0006\u0001\0d\o?\""\0$?##STA\r\nSystemLevel:Run\r\nstatus:1\r\nSensor Value:12.45\r\n................\r\nSTOP##";
      byte[] bts = Encoding.UTF8.GetBytes(str);
      var g23to40 = getRange(bts, 22, 39);
      Console.WriteLine(Encoding.UTF8.GetString(g23to40));
    }
    public static byte[] getRange(byte[] a, int s, int e = -1) {
      if (e == -1) { e = a.Length-1; }
      if (e <= s) { return new byte[]{}; }
      byte[] r = new byte[e-s];
      int bi = 0;
      for (int i = s; i != e; i++) {
        if (i >= s && i <= e) {
          r[bi] = a[i];
          bi++;
        }
      }
      return r;
    }
  }
}

score 0 · Answer 3 · answered Jan 08 '20 at 10:45

in my opinion:

i would process it as byte array and remove header/checksum stuff/...

byte.Skip(..).Take(...)

give that bytearray to a function, which converts to right string format, and does the over stuff.

if you search for stuff in the byte array: I guess you are not working with much data (100Mb+). Cause Linq isnt the fastet.

Byte<Span>

ist the faster one (.net Core)

and the fastest is found here:

byte[] array pattern search

(the Buffer.BlockCopy thing)

Best method to parse byte array with required chars only c#

3 Answers3