无法在MIT App Inventor 2中汇总数据

Question

So when I try to sum the variable Consum with Test (received from bluetooth), the blue block does not allow such operation. If this is in normal coding program it would be:

Consume = Consume + Test;

Any help?

Answer 1

you only can add data, if data is available
therefore in the Clock.Timer event add another if statement like this

if BluetoothClient1.BytesAvailableToReceive > 0
then...

Answer 2

Here is what App Inventor says about the Receive Text function:

Receive text from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

This function receives bytes from the Bluetooth component and returns text, which cannot be added unless the text is a number. If you look at the error message that you get, it should tell you that you are adding a string and a number. You could have also used the Do It option in the emulator or companion to see the result that the Receive Text procedure outputs.

Here is an example of the proper way to use this block: you should set the test variable to bytes available to receive and then remove all available bytes by using receive text with the available bytes.