Windows Forms Visual C++ 2010 - while loop causes crash?

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C++/CLI

Windows

.NET

, +

First of all, I'm pretty new to C++.

I'm writing a program to communicate with a device via the serial port.

Radio buttons are used to toggle the mode and the program is supposed to execute a loop until a radio button is changed. As soon as the button is pressed to toggle onto Pmode, the program crashes and nothing can be pressed.

I've been looking online and people with similar problems have suggested using Invoking but I don't really understand how to use this?

Here's the relevant bit of code: thanks for any advice

private: System::Void rbCMode_CheckedChanged(System::Object^  sender, System::EventArgs^  e)
{
  if(rbCMode->Checked)
  {
    //set to command mode
    String^ message = "Set_Mode_C";
    mySerialPort->WriteLine(String::Format("{0}", message));

    //wait for OK confirmation
    OKCheck();
  }
  else //Pmode must be checked
  {
    //set to polling mode mode
    String^ message = "Set_Mode_P";
    mySerialPort->WriteLine(String::Format("{0}", message));
    // wait for OK confirmation
    OKCheck();
  }
             
  while(rbPMode->Checked == true)
  {   
    ReadAngles(xangle, yangle, x_angle_text, y_angle_text); //read the angles
    txtXDisplay->Text=x_angle_text; //update displays
    txtYDisplay->Text=y_angle_text;
  }
}

 

static void ReadAngles(double^ %xangle, double^ %yangle, String^ %x_angle_text, String^ %y_angle_text)
{
  //read from the buffer
  //check the number of bytes in buffer, dont read unless 19 bytes
  int databytes = mySerialPort->BytesToRead;
  while (databytes < 19) 
  {
    databytes = mySerialPort->BytesToRead;
  }

  //if the received string is "OK" then reject
  String^ buffer = mySerialPort->ReadLine();
  while (buffer->Length <= 5)
  {
    buffer = mySerialPort->ReadLine();
  }

  //split string into correct parts and convert to double
  x_angle_text = buffer->Substring(2,6);
  y_angle_text = buffer->Substring(11,6);
  xangle = System::Convert::ToDouble(x_angle_text);
  yangle = System::Convert::ToDouble(y_angle_text);
  return;
}