Question

I have managed to fetch values via RS232 from a temperature sensor. The expected values are to be added to the database for further manipulation. Here is the code.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
using System.IO.Ports;

namespace SimpleSerial
{

    public partial class Form1 : Form
    {
        // Add this variable 
        MySqlConnection conn = null;
        float tempvalue;
        string RxString;

        public Form1()
        {
            InitializeComponent();
        }
        public void dbconnect()
        {
            string cs = @"server=xxx.x.x.xx;userid=uuuuuu;password=xxxxx;database=project";
            try
            {
                conn = new MySqlConnection(cs);
                conn.Open();
                MySqlCommand cmd = new MySqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = "INSERT INTO temp(value) VALUES(@value) ";
                cmd.Prepare();
                cmd.Parameters.AddWithValue("@value", tempvalue);
                cmd.ExecuteNonQuery();
                //Console.WriteLine("MySQL version : {0}", conn.ServerVersion);

                //MessageBox.Show("DB Connected");
            }
            catch (MySqlException ex)
            {
                Console.WriteLine("Error: {0}", ex.ToString());
                MessageBox.Show("Error: {0}", ex.ToString());
            }
            finally
            {
                if (conn != null)
                {
                    conn.Close();
                }
            }

        }

        private void buttonStart_Click(object sender, EventArgs e)
        {
            serialPort1.PortName = "COM2";
            serialPort1.BaudRate = 9600;
            serialPort1.Open();
            if (serialPort1.IsOpen)
            {
                buttonStart.Enabled = false;
                buttonStop.Enabled = true;
                textBox1.ReadOnly = false;
            }

        }

        private void buttonStop_Click(object sender, EventArgs e)
        {
            if (serialPort1.IsOpen)
            {
                serialPort1.Close();
                buttonStart.Enabled = true;
                buttonStop.Enabled = false;
                textBox1.ReadOnly = true;
            }

        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (serialPort1.IsOpen) serialPort1.Close();
        }

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            // If the port is closed, don't try to send a character.
            if (!serialPort1.IsOpen) return;

            // If the port is Open, declare a char[] array with one element.
            char[] buff = new char[1];

            // Load element 0 with the key character.
            buff[0] = e.KeyChar;

            // Send the one character buffer.
            serialPort1.Write(buff, 0, 1);

            // Set the KeyPress event as handled so the character won't
            // display locally. If you want it to display, omit the next line.
            e.Handled = true;
        }

        private void DisplayText(object sender, EventArgs e)
        {
            tempvalue = float.Parse(RxString);    
            dbconnect();
            textBox1.AppendText(RxString);
        }

        private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            RxString = serialPort1.ReadExisting();
            this.Invoke(new EventHandler(DisplayText));

        }
    }
}

Kindly note:

    tempvalue = float.Parse(RxString);    
    dbconnect();
    textBox1.AppendText(RxString);

is the value I would like to manipulate. Current output is like 56.1234557.4323253.34221 . The values of interest are two digits on the left after the every ‘.’.I would like to get this values has 56 57 53 etc. I have tried round it seems not to be the best option here. Since it is from a serial port, the way the values are read make me loose some bits.
Is there a way I can separate the Xs and Ds in XX.DDDDD and use the XX to populate the database? I have tried RxString.Split('.'). Maybe I did not do it right. Someone kindly help. Thanks

Answer 1

You can use Regex to extract the interesting parts of the string

MatchCollection matches =
    Regex.Matches("56.1234557.4323253.34221", @"\d\d(?=\.)");
foreach (Match match in matches) {
    Console.WriteLine(match.Value);
}

I used the regex pattern find(?=suffix) which matches a position preceding a suffix. \d\d matches two digits and \. matches the decimal point.