README.md

Lesson 08 — Multiple Targets

What you'll learn

How to define multiple build targets (all, clean, rebuild) and why .PHONY matters.

Conventional targets

Most Makefiles define these standard targets:

Target	Purpose
all	Build everything (the default — must be first in the file)
clean	Remove all build artifacts
rebuild	Clean then build from scratch
test	Build and run tests (lesson 15)
install	Copy files to system directories

Why app instead of main?

In lessons 01–07 the executable was called main — matching the single source file. From this lesson onward, projects have multiple source files (logger, app, etc.), so the executable is named app to reflect that it's a complete application, not just one file. The name is arbitrary — what matters is that TARGET holds it.

.PHONY — why it matters

.PHONY: all clean rebuild

Without .PHONY, if a file named clean happened to exist in your directory, Make would check its timestamp, see it's "up to date," and skip the recipe. .PHONY tells Make these targets are commands, not files — always run them.

Default target

The first target in the Makefile is what make (with no arguments) builds. Convention is to name it all:

all: $(TARGET)    # this is the default target

The Makefile

.PHONY: all clean rebuild

all: $(TARGET)

$(TARGET): $(OBJS)
	$(CXX) -o $@ $^

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

clean:
	rm -f $(TARGET) $(OBJS) $(DEPS)

rebuild: clean all

Try it

cd 08_multiple_targets
make              # builds the app (default target: all)
./app             # [INFO]  Application started ...
make clean        # removes app, .o, and .d files
make rebuild      # cleans, then builds fresh

Files

File	Purpose
include/logger.hpp	Declares log_info() and log_error()
src/logger.cpp	Implements them with [INFO]/[ERROR] prefixes
src/main.cpp	Logs several messages
Makefile	all, clean, rebuild targets with .PHONY