Hi-
I am trying to alter a library and I understand that I need to delete the .o file for it before I can compile the changes, but I can't find the .o file. As a matter of fact, I can't find ANY .o files. A search of my computer only shows .o files for arduino residing in \arduino-0021\hardware\tools\avr\avr\lib and below, none of which seem to apply with the general libraries, and none of which have a build date differently from when I installed the package on my computer. Can someone help me out? Thanks for your patience.
Open a sketch (any sketch). Hold down a "Shift" key and click the Arduino "Verify" button. You will see that every single one of the Arduino core source files is compiled into an object file and the object files are inserted into a brand new library file in a temporary directory. Then any files from any libraries that your sketch explicitly includes are compiled into object files and then the cpp file generated by the sketch is compiled into an object file. Finally, everything is linked together into an executable.
If you recompile, everything is done afresh. When you leave the Arduino IDE, the temporary files may disappear, but they wouldn't have been used again anyhow.
Bottom line: All library source files are compiled each and every time you recompile your source. There is no need to delete any library or object files from previous compilations.
Regards,
Dave
The instructions for deleting any existing .o files are for older versions of the IDE. Deleting the .o file forces a rebuild of the library.
Newer versions of the IDE rebuild all files every time, so deleting (or keeping) the .o files is no longer necessary.