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Sample makefile

bgstack15

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Last modified: 2022-09-30

Here is a quick little makefile I use in small projects. It compiles all .cpp files, and then links all .o files into a single binary. It also includes a nice "list" target, which lists all the available targets. I realize bash tab auto-complete usually is good enough, but for programmatic uses, make list is helpful.

# references:
#    BUILD_DIR and per-.cpp file https://spin.atomicobject.com/2016/08/26/makefile-c-projects/
awkbin     :=$(shell which awk)
cpbin      :=$(shell which cp)
echobin    :=$(shell which echo)
findbin    :=$(shell which find)
grepbin    :=$(shell which grep)
installbin :=$(shell which install)
rmbin      :=$(shell which rm)
sedbin     :=$(shell which sed)
sortbin    :=$(shell which sort)
truebin    :=$(shell which true)

CXX = g++

# to get full debug symbols, add to both FLAGS: -g
# to make all warnings act as errors: -Wall -Weffc++ -Wextra -Wsign-conversion -Werror
CXXFLAGS = -g -std=c++17 -Wall -Weffc++ -Wextra -Wsign-conversion -Werror

# to remove all debug symbols: -s
# to add full debug symbols: -g
LDFLAGS = -g

ifneq (,$(DEBUG))
CXXFLAGS+=-DDEBUG=$(DEBUG)
endif

src = $(wildcard *.cpp)
obj = $(src:.cpp=.o)

BUILD_DIR ?= .

OUTEXE = mine

all: $(OUTEXE)

$(obj):

$(BUILD_DIR)/%.o: %.cpp
    $(CXX) -c $(CXXFLAGS) -o $@ $<

# link
$(OUTEXE): $(obj)
    $(CXX) -o $@ $^ $(LDFLAGS)

.PHONY: clean cleanall list

list:
    @$(MAKE) -pRrq -f $(lastword $(MAKEFILE_LIST)) : 2>/dev/null | ${awkbin} -v RS= -F: '/^# File/,/^# Finished Make data base/ {if ($$1 !~ "^[#.]") {print $$1}}' | ${sortbin} | ${grepbin} -E -v -e '^[^[:alnum:]]' -e '^$@$$' -e '\.(cp*|o)'

clean:
    rm -f $(obj)

cleanall:
    rm -f $(obj) $(OUTEXE)

If you run make DEBUG=1 make will then run the compiler with -DDEBUG=1 which is useful if you add #ifdef DEBUG sections to your source code.

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