Styjun

I'm getting the information by reading the card, but how can I just get the tag number as int?

 public Form1()
 
 InitializeComponent();
 

 private void Form1_Load(object sender, EventArgs e)
 
 if (!serialPort1.IsOpen)
 
 serialPort1.Open();
 serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived);
 

 MessageBox.Show("Success");
 
 private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
 
 Control.CheckForIllegalCrossThreadCalls = false;
 SerialPort sp = (SerialPort)sender;
 string indata = sp.ReadExisting();
 textRFID.Text += indata;
 

This is the string I need to parse:

"RFID tag detected Tag Type:tMifare One (S50) The tag's number is:t235717311 Read Checksum:t238 Calculated Checksum:t238"

Thanks to @haldo I can receive my tag number but it gives "object reference not set to an instance of an object" error and I put try catch, when I press ok to error, it goes and output is as I wanted. How can we remove this error?

Here is my editing code :

private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
 
 Control.CheckForIllegalCrossThreadCalls = false;
 string contains = "The tag's number is:";
 SerialPort sp = (SerialPort)sender;
 string indata = sp.ReadExisting();
 int tagNumber = 0;
 try
 
 indata.Split(Environment.NewLine.ToCharArray()) // split on newline chars
 .FirstOrDefault(s => s.Contains(contains)) // get first string matching pattern above 
 .Split(':') // split on ':'
 .FirstOrDefault(x => int.TryParse(x, out tagNumber)); // return first successful try parse
 
 catch (Exception ex) MessageBox.Show(ex.Message); 
 textRFID.Text = tagNumber.ToString(); 
 

Why don't you use String manipulators like Substring or String.split(''). you would get the Tag number and then use Convert.ToInt(your tag number here) to convert into INT. By default it is string. you need to convert it to Integer

You could use regex to look for the pattern and capture the group of digits after "The tag's number is:", then parse that captured string as an int. Something like this:

string pattern = "The tag's number is:(\d+)";
string indata = "blah blah nasdfasdfasdfnThe tag's number is:123389882nasdfsadfnfgjdjgjgd";
var matches = Regex.Match(indata, pattern);
int? tagNumber = null;

if (matches.Success)

 var grp = matches.Groups[1];
 string num = grp.Value;
 tagNumber = int.Parse(num);


// tagNumber is 123389882