makefile for building c/c++ projects

build.mk

# overridable variables:
#   * project          -> defaults to parent dir basename
#   * src-root         -> defaults to src
#   * out-root         -> defaults to bin
#   * debug            -> define it to anything for debug mode
#   * platform         -> possible values are win32,osx,linux,ios,iossim
#   * inc, inc-*       -> where * is the platform
#   * lib, lib-*       -> where * is the platform
#   * flg, flg-*       -> where * is the platform
#   * ios.version      -> installed sdk version
#   * ios.version.min  -> minimum sdk version
#   * ios.plist        -> file that will be copied as Info.plist
#   * ios.bundle.files -> additional files to put along the executable file

project ?= $(notdir $(shell pwd))
src-root ?= src
out-root ?= bin
cxx ?= g++
cc ?= gcc

# try to detect platform if not given

ifndef platform
ifeq ($(shell uname | grep 'MINGW32_NT' -c),1)
platform ?= win32
endif
ifeq ($(shell uname | grep 'Linux' -c),1)
platform ?= linux
endif
ifeq ($(shell uname | grep 'Darwin' -c),1)
platform ?= osx
endif
endif # platform

# define extra stuff for ios

ifeq ($(platform),ios)
ios := true
ios.version.min ?= 4.0
ios.version ?= $(shell xcodebuild -showsdks | grep iphoneos | sed "s|.*iphoneos||")
ios.xcode.path := $(shell xcode-select --print-path)
ios.dev.path := $(ios.xcode.path)/Platforms/iPhoneOS.platform/Developer
ios.sdk.path := $(ios.dev.path)/SDKs/iPhoneOS$(ios.version).sdk
ios.arch := armv7
ios.flags := -isysroot $(ios.sdk.path) -arch $(ios.arch) -miphoneos-version-min=$(ios.version.min)
endif

ifeq ($(platform),iossim)
ios := true
ios.version.min ?= 4.0
ios.version ?= $(shell xcodebuild -showsdks | grep iphoneos | sed "s|.*iphoneos||")
ios.xcode.path := $(shell xcode-select --print-path)
ios.dev.path := $(ios.xcode.path)/Platforms/iPhoneSimulator.platform/Developer
ios.sdk.path := $(ios.dev.path)/SDKs/iPhoneSimulator$(ios.version).sdk
ios.arch := i386
ios.flags := -isysroot $(ios.sdk.path) -arch $(ios.arch) -mios-simulator-version-min=$(ios.version.min)
endif

ifdef ios
flg += $(ios.flags)
endif

# set the name of the output executable

binary-postfix-win32 := .exe
$(eval binary-postfix := $$(binary-postfix-$(platform)))
out-file := $(project)$(binary-postfix)

# define _DEBUG if compiling on debug mode and add some extra flags

ifdef debug
flg += -g -D_DEBUG -Wall
out-dir := $(out-root)/$(platform)-d
else
flg += -g -O3 -Wall
out-dir := $(out-root)/$(platform)
endif

# consolidate all the platform specific options into inc,lib,flg variables

$(eval inc += $$(inc-$(platform)))
$(eval lib += $$(lib-$(platform)))
$(eval flg += $$(flg-$(platform)))

# find all directories under src-root and set matching directories for dependency and object files

src-dirs := $(shell find $(src-root) -depth -type d)
obj-dirs := $(patsubst $(src-root)%,$(out-dir)/obj%,$(src-dirs))
dep-dirs := $(patsubst $(src-root)%,$(out-dir)/dep%,$(src-dirs))

# make a list of directories to be created

out-dirs := $(out-dir)/ $(obj-dirs) $(dep-dirs)

ifdef ios
out-dirs += $(out-dir)/bundle
out-dirs += $(out-dir)/bundle/Documents
out-dirs += $(out-dir)/bundle/Library
out-dirs += $(out-dir)/bundle/tmp
out-dirs += $(out-dir)/bundle/$(project).app
endif

# define extensions used for c++

cxx-ext := cpp cxx cc

ifdef ios
cxx-ext += m mm
endif

# find all source files under the source directories and make matching lists of dependency and objects files

src-cxx := $(foreach d,$(src-dirs),$(foreach e,$(cxx-ext),$(wildcard $d/*.$e)))
src-cc := $(foreach d,$(src-dirs),$(wildcard $d/*.c))

obj-cxx := $(patsubst $(src-root)%,$(out-dir)/obj%.o,$(src-cxx))
obj-cc := $(patsubst $(src-root)%,$(out-dir)/obj%.o,$(src-cc))

dep-cxx := $(patsubst $(src-root)%,$(out-dir)/dep%.d,$(src-cxx))
dep-cc := $(patsubst $(src-root)%,$(out-dir)/dep%.d,$(src-cc))

# main target on ios is ios.bundle

ifdef ios
out-file := bundle/$(project).app/$(out-file)
ios.outdir := $(out-dir)/bundle/$(project).app

ios.bundle: $(out-dir)/$(out-file) $(ios.outdir)/Info.plist \
	$(addprefix $(ios.outdir)/,$(ios.bundle.files)) | $(out-dirs)

.PHONY: ios.bundle

ifdef ios.plist
$(ios.outdir)/Info.plist: $(ios.plist)
	cp -f $(ios.plist) $@
else
doctype := <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" \
	"http://www.apple.com/DTDs/PropertyList-1.0.dtd">

$(ios.outdir)/Info.plist: makefile
	@echo '<?xml version="1.0" encoding="UTF-8"?>'            > $@
	@echo '$(doctype)'                                       >> $@
	@echo '<plist version="1.0">'                            >> $@
	@echo '  <dict>'                                         >> $@
	@echo '    <key>CFBundleDevelopmentRegion</key>'         >> $@
	@echo '    <string>English</string>'                     >> $@
	@echo '    <key>CFBundleDisplayName</key>'               >> $@
	@echo '    <string>$(project)</string>'                  >> $@
	@echo '    <key>CFBundleExecutable</key>'                >> $@
	@echo '    <string>$(project)</string>'                  >> $@
	@echo '    <key>CFBundleIconFile</key>'                  >> $@
	@echo '    <string>Icon.png</string>'                    >> $@
	@echo '    <key>CFBundleIdentifier</key>'                >> $@
	@echo '    <string>com.example.$(project)</string>'      >> $@
	@echo '    <key>CFBundleInfoDictionaryVersion</key>'     >> $@
	@echo '    <string>6.0</string>'                         >> $@
	@echo '    <key>CFBundleName</key>'                      >> $@
	@echo '    <string>$(project)</string>'                  >> $@
	@echo '    <key>CFBundlePackageType</key>'               >> $@
	@echo '    <string>APPL</string>'                        >> $@
	@echo '    <key>CFBundleSignature</key>'                 >> $@
	@echo '    <string>????</string>'                        >> $@
	@echo '    <key>CFBundleShortVersionString</key>'        >> $@
	@echo '    <string>1.0</string>'                         >> $@
	@echo '    <key>CFBundleVersion</key>'                   >> $@
	@echo '    <string>1.0.0</string>'                       >> $@
	@echo '    <key>UIStatusBarStyle</key>'                  >> $@
	@echo '    <string>UIStatusBarStyleBlackOpaque</string>' >> $@
	@echo '    <key>LSRequiresIPhoneOS</key>'                >> $@
	@echo '    <true/>'                                      >> $@
	@echo '  </dict>'                                        >> $@
	@echo '</plist>'                                         >> $@
endif # ios.plist

define ios.copyfiles
$(ios.outdir)/$1: $1
	cp -rf "$1" "$(ios.outdir)/"
endef

$(foreach f,$(ios.bundle.files),$(eval $(call ios.copyfiles,$f)))
endif # ios

# target for main executable

$(out-dir)/$(out-file): $(obj-cxx) $(obj-cc) | $(out-dirs)
	@echo "Linking $@..."
	@$(cxx) -o $@ $(obj-cxx) $(obj-cc) $(lib) $(flg)

# create required directories

$(out-dirs):
	@mkdir -p $@

# make-obj(compiler,source)

define make-obj
$(out-dir)/obj/$2.o: $(src-root)/$2 | $(out-dirs)
	@echo "Compiling $$<..."
	@$1 -o $$@ -MF"$(out-dir)/dep/$2.d" -MMD -MP \
		-MT"$(out-dir)/dep/$2.d $(out-dir)/obj/$2.o" $(inc) $(flg) -c $$<
endef

# create a rule for each source file using make-obj template

$(foreach s,$(src-cxx),$(eval $(call make-obj,$(cxx),$(patsubst $(src-root)/%,%,$s))))
$(foreach s,$(src-cc),$(eval $(call make-obj,$(cc),$(patsubst $(src-root)/%,%,$s))))

# include generated dependency files if they exist

ifneq ($(MAKECMDGOALS),clean)
-include $(dep-cxx) $(dep-cc)
endif

# cleanup

clean:
	@rm -rf $(out-root)
.PHONY: clean

A comprehensive and easy to use C++ Makefile example can also be found here:

https://www.partow.net/programming/makefile/index.html