Just tried putting a handful of functions into another file, so rather than having one .c file, have two .c files and a .h file.

Cut handful of functions, put them into the second .c file. Cut their declarations, put those in the .h file. Put
#include "second-file.h"
at the top of the first .c file

I'm getting error: expected ‘)’ before ‘*’ token errors for each function but they were fine before I put them in the second file. What's going on there? Don't understand how putting them in another file could make any difference?