Question

In the following (cut down) make file, the dependencies are at the bottom. This is part of an actual make file that i am writing. In the real case there is a header file dependent on another header.

I haven’t been able to find the answer elsewhere so… would i need to include a line at the bottom under dependencies to the effect of “swap.h: other.h”?

SRC =       swap.c other.c etc
OBJ =       swap.o other.o etc
EXE =       swap

$(EXE): $(OBJ)
        $(CC) $(CFLAGS) -o $(EXE) $(OBJ) -lm

## Dependencies

swap.o: swap.h other.h
other.o:    other.h

Thanks!

Answer 1

Since there nothing to do for swap.h if other.h changes even if the first #includes the seconds, the short answer is no.

… But, if some C source includes swap.h and swap.h includes other.h, a change in other.h will affect /the object needed to be generated from the said C source.

Typically, however, you don’t want to maintain your header dependency manually. It is laborious and error prone.

There are several ways for generating these dependencies automatically.

I can recommend the Advanced Auto-Dependency Generation paper. This method is not perfect, but it is as good as you can get with Makefiles.