makefile-example

Good Makefile for C/C++

Make

$ make clean
rm -f ./src/main.o ./src/mod/mod.o app

$ make depend
g++ -I./include -MM ./src/main.cpp ./src/mod/mod.cpp > Makefile.depend

$ make -j4
g++ -O2 -Wall -I./include   -c -o src/main.o src/main.cpp
g++ -O2 -Wall -I./include   -c -o src/mod/mod.o src/mod/mod.cpp
g++ -lm -o app ./src/main.o ./src/mod/mod.o

$ make run
Hello, world!

tips

List the source files

Use find command in order to list recursively.

SRCS = $(shell find ./src -type f -name *.cpp)

Resolve dependencies by gcc -MM option

$ g++ -I./include -MM ./src/main.cpp ./src/mod/mod.cpp
main.o: src/main.cpp include/main.h include/mod/mod.h
mod.o: src/mod/mod.cpp include/mod/mod.h

Sadly, outputted rule is only filename. So, add directory path from first cpp file by sed.

src/main.o: src/main.cpp include/main.h include/mod/mod.h
src/mod/mod.o: src/mod/mod.cpp include/mod/mod.h

Makefile includes this result for incremental build.

Parallel compilation by gcc -j option

-j<max number of parallel job>

It's better to use the same number as the number of CPU cores. ;If 4 cores, run make -j4

This option requires dependency chain in Makefile. For example, you should run following when clean and build.

$ make clean -s && make -j4