makefile generic version

Among the actual program file is large, this time to classify files, divided into header files, source files, object files, executable files. That is usually a file by file type them in a different directory, this time Makefile requires unified management of these files, the production target files in the target directory, the executable file into the executable directory.

DIR_INC = ./include
DIR_SRC = ./src
DIR_OBJ = ./obj
DIR_BIN = ./bin

SRC = $(wildcard ${DIR_SRC}/*.c)
OBJ = $(patsubst %.c,${DIR_OBJ}/%.o,$(notdir ${SRC}))

TARGET = main

BIN_TARGET = ${DIR_BIN}/${TARGET}

CC = gcc
CFLAGS = -g -Wall -I${DIR_INC}

${BIN_TARGET}:${OBJ}
    $(CC) $(OBJ) -o $@

${DIR_OBJ}/%.o:${DIR_SRC}/%.c
    $(CC) $(CFLAGS) -c $< -o $@

.PHONY:clean
    
clean:
    find ${DIR_OBJ} -name *.o -exec rm -rf{}

Explained as follows:

(1) Makefile symbols in $ @, $ ^, $ <meaning:
　　$ @ represents the target file
　　$ ^ represents all dependent files
　　$ <represents a dependency file
　　$ express new list also rely on documents than the target?

(2) wildcard, notdir, patsubst meaning:

　　wildcard: wildcard expansion
　　notdir: Remove Path
　　patsubst: Alternatively Wildcard

SRC = $(wildcard *.c)

Equal to the specified compile all .c files in the current directory, if there are subdirectories, such as subdirectories as inc, then add a wildcard function, like this:

SRC = $(wildcard *.c) $(wildcard inc/*.c)

(3) gcc -I -L -l distinction:

       gcc -o hello hello.c -I /home/hello/include -L /home/hello/lib -lworld

       The above sentence said in compiling hello.c -I / home / hello / include express the / home / hello / include directory as the first directory to find header files,

　　 Looking order is: / home / hello / include -> / usr / include -> / usr / local / include

 　　-L / home / hello / lib represents the / home / hello / lib directory as the first to find catalog file,

　　 Looking order is: / home / hello / lib -> / lib -> / usr / lib -> / usr / local / lib

       -lworld looking libworld.so represent dynamic library files in lib path above in (if gcc compiler option to join the "-static" looking libworld.a represents static library file)