Comport Reading and Padding

Question

Hello all. I hope someone may be able to help me with two problems I have that I do not understand.

private void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
    {
        // If the com port has been closed, do nothing
        if (!comport.IsOpen) return;

        // This method will be called when there is data waiting in the port's buffer

        // Determain which mode (string or binary) the user is in

            // Read all the data waiting in the buffer
            string data = comport.ReadExisting();
            textBox1.AppendText(data);
            textBox1.ScrollToCaret();
            //scnbutton.PerformClick();

            // Display the text to the user in the terminal


    }

I am Dealing with barcodes. When my scanner scans the barcode it returns S08A07934068721. It returns this value every time the UPC is 07934068721 which is the value I wish to append to the textbox.

     string data1= data.Substring(4);
     textBox1.AppendText(data1);

This is an example of what have tried to use to substring it.

Every time I try to substring the string data it ends up breaking into pieces and I'm not sure how to stop it. After I get this fixed then I will have a problem with the code below

textBox1.Text = textBox1.Text.PadLeft(13, '0');

This works great and always pads 13 digits. But when the UPC or something types has a 0 in the front it drops down to 12 digits why is this?

Answer 1

After Much Playing around i discovered there there where invisible character in my textbox so using

textBox1.Text = textBox1.Text.Trim();

This got rid of the invisible characters allowing the padding to work correctly, i then changed my data received event to be on a timer to avoid cross thread issues like this

private void timer3_Tick(object sender, EventArgs e)
    {

        data = comport.ReadExisting();

        try
        {
            if (data != "")
            {
                textBox1.Clear();
                textBox1.AppendText(data);
                timer3.Stop();
                scan();
                timer3.Start();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
        comport.DiscardInBuffer();

    }

My program is now working like i need. Thank you user2019047 for your help

Answer 2

I tried your string in a piece of code and it all worked.

string data = "S08A07934068721";                // results

string data1 = data.Substring(4);               //   07934068721

// test if padding correctly
string padded = data1.PadLeft(13, '0');         // 0007934068721

// textbox tbPadded is empty before adding text  
tbPadded.AppendText(data1);                     //   07934068721

// pad text
tbPadded.Text = tbPadded.Text.PadLeft(13, '0'); // 0007934068721