C# scan bluetooth LE devices

Question

I use C# to find Bluetooth Low Enegergy devices on Windows 10. When I run the following codes, I met such an error:

"An exception of type 'System.ArgumentOutOfRangeException' occurred in mscorlib.dll but was not handled in user code".

The line of the error is Debug.WriteLine("Found device: " + devices[0].Id);

I do not know why it is out of range. Thanks!

   namespace BluetoothLE
    {
        /// <summary>
        /// Interaction logic for MainWindow.xaml
        /// </summary>
        public partial class MainWindow : Window
        {

            public MainWindow()
            {
                InitializeComponent();
            }

            private async void LookForPairedDevices()
            {

                // Get BLE devices paired with Windows
                DeviceInformationCollection devices = await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector());

                Debug.WriteLine("Found device: " + devices[0].Id);


            }
        }

    }

Answer 1

Your error is on this line:

Debug.WriteLine("Found device: " + devices[0].Id);

If you debug you're code, you'll see that devices has a length of 0 and you're trying to access the property id of the first one (which doesn't exist).

You may want to consider using a foreach loop to see what is returned like so:

foreach(var device in devices){
    Debug.WriteLine("Found device: " + device.Id);
}