Implementation of Arduino F() macro

问题:

I'm trying to understand what the F() macro in Arduino actually does with PGMEM and RAM and what are the runtime implications. Can someone point me at the file that defines this macro?

回答1:

This may be an older version, but one place where it is defined is Wstring.h as in here.

You can find it yourself: if you installed Arduino you can search the installation directory. WString.h should be in hardware\arduino\cores\arduino\