C标头中包含include

Question

I'm going rounds with the compiler right now, and I want to make sure the problem isn't a fundamental misunderstanding of how header files. If I include a header file, and that header file has includes in it (like <stdbool.h> or <stdio.h> , etc...), there shouldn't be any issue on the dependent C file, right? The preprocessor should just insert the assembled code accordingly when I call my makefile, by my understanding. Am I mistaken?

To reiterate:

• Say I have a main.c with prototype.h .

• prototype.h has in it all of my usual includes for libraries and what-not.

• I have a couple other C files ( secondary.c and tertiary.c , for instance), both of which need the usual libraries, as well, and may or may not need some of the prototypes and also have their own header files.

All I'd need to do is include prototype.h in each of the C files, correct?

Also, in that instance, if I were making .o file using the -c flag of gcc in my makefile , would I need to update the dependency in the target of the makefile ?

I thought I had a solid handle on this when I started, but now I'm thoroughly confused.

Answer 1

That is questions with multiple answers.

In simple case you only include headers if they are used in .c file. Headers are dependencies for compilation so for Make you just put it in the same bucket where .c files using those.

For big projects to speedup compilation you may use what called 'precompiled header'. You must include the same header file into every source file, compiler will only process that header once. That is very useful when headers are complicated (eg boost library)