# Global target; when 'make' is run without arguments, this is what it should do
all: helloworld

# These variables hold the name of the compilation tool, the compilation flags and the link flags
# We make use of these variables in the package manifest
CC = gcc
CFLAGS = -Wall
LDFLAGS = 

# This variable identifies all header files in the directory; we use it to create a dependency chain between the object files and the source files
# This approach will re-build your application whenever any header file changes. In a more complex application, such behavior is often undesirable
DEPS = $(wildcard *.h)

# This variable holds all source files to consider for the build; we use a wildcard to pick all files
SRC = $(wildcard *.c)

# This variable holds all object file names, constructed from the source file names using pattern substitution
OBJ = $(patsubst %.c, %.o, $(SRC))

# This rule builds individual object files, and depends on the corresponding C source files and the header files
%.o: %.c $(DEPS)
        $(CC) -c -o $@ $< $(CFLAGS)

# To build 'helloworld', we depend on the object files, and link them all into a single executable using the compilation tool
# We use automatic variables to specify the final executable name 'helloworld', using '$@' and the '$^' will hold the names of all the
# dependencies of this rule
helloworld: $(OBJ)
        $(CC) -o $@ $^ $(LDFLAGS)

# To clean build artifacts, we specify a 'clean' rule, and use PHONY to indicate that this rule never matches with a potential file in the directory
.PHONY: clean

clean:
        rm -f helloworld *.o