noInterrupts() in .cpp files

Arduino’s built-in functions “interrupts()” and “noInterrupts()” aren’t recognized if I attempt using them in .cpp files. What do I need to #include in a C file to get these working? Sorry if this is an obvious question, but I’ve searched the online documentation without finding an answer. If it’s answered somewhere, a link would be sufficient. Thanks.

BrunettoLatini: Arduino's built-in functions "interrupts()" and "noInterrupts()" aren't recognized if I attempt using them in .cpp files. What do I need to #include in a C file to get these working?

You do include Arduino.h already, do you?

#include <Arduino.h>

happens automatically for your .ino file, but not for libraries.

Thank you very much!