当没有连接COM（串行）端口或串行监视器打开时，arduino是否运行打印功能（print，println，printf等）？

Question

Im wondering the print statements in my code are taking up processing cycles when the robot isn't connected to the com port. I am running a time sensitive process and have reason to believe the execution of these lines could be slowing my bot down.

Answer 1

Yes It will take processing time even if no serial monitor or other device is connected.

A good practice is to a have a #define pre-processor directive in your code indicating whether you are debugging or not.

eg

#define DEBUG_PHASE

#ifdef DEBUG_PHASE
printf(...);
#endif

Answer 2

Of course they are. The MCU still goes through the actions of parsing the format string and sending serial data even when nothing is listening.