header files in C

Should you have to include a header file into its own library? I can't understand why I sometimes, but not always, get compile errors because it's not getting the header file prototypes before it compiles the libraries.

Uh, C doesn't need prototypes. All functions are assumed to return machine-word sized ints, and take variable number of args. Additionally, all functions are 'global' unless declared as static, whereby they're only visible in the unit module they're defined in. Any symbols which can't be resolved at compile-time are done so at runtime.

Then again, I have no idea what OP is trying to ask.