How to include precompiled .h.gch headers using g++

Question

Suppose I have A.h, A.cpp, B.h and B.h.gch (I have downloaded B from Internet)

How can I compile my code (and create an executable) ?

I have an error when I do

g++ -c B.h.gch

`g++: warning: B.h.gch: linker input file unused because linking not done` It's a warning but the .o is not generated. — Mourad Qqch, Dec 08 '16 at 20:24
I usually do `g++ -c sources.cpp` and then, `g++ -o executable sources.o` but I've never encountered a .h.gch before and Google can't help me for now. (Sorry if my english is bad) — Mourad Qqch, Dec 08 '16 at 20:27

score 2 · Accepted Answer · edited May 23 '17 at 12:24

You can practically have only one single precompiled header myheader.h and quite often that single header is including other ones. See this answer for more.

You compile that C++ header with g++ -c myheader.h (and other relevant options, notably -O , -g, -Wall , -Idirname ...; they should be the same as for your object files). In practice you should have a Makefile and use make (run once make -p to understand the builtin rules). The CXXFLAGS there should be used both for object files and for the precompiled header.

You don't change any #include directive (but in practice all your *.cc or *.cpp files should have only one).

Read also the Precompiled headers section.

Thank you for your answer :-) – Mourad Qqch Dec 08 '16 at 20:52 — Mourad Qqch, Dec 08 '16 at 20:52

How to include precompiled .h.gch headers using g++

1 Answers1