如何使用包含和库创建 Makefile？

Question

我正在尝试为我的 C++ 项目创建 Makefile。

我的main.cpp 包含此自定义包括：

#include <mysql_connection.h>
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>

对于我使用的编译：

g++ -stdlib=libc++ -o app.cgi -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc -L/usr/local/mysql-connector-c++/lib64 main.cpp -lmysqlcppconn

现在我需要添加

#include "tinyxml2/tinyxml2.hpp"

最简单的方法是创建Makefile。我写道：

CC = g++

CFLAGS = -Wall -g -std=c++11

INCLUDES = -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc

LDLIBS = -L/usr/local/mysql-connector-c++/lib64 -lmysqlcppconn

SRCS = main.cpp ./tinyxml2/tinyxml2.cpp 

OBJS = $(SRCS:.cpp=.o)

MAIN = main.cgi

#
# The following part of the makefile is generic
#

.PHONY: depend clean

all:    $(MAIN)

$(MAIN): $(OBJS) 
        $(CC) $(CFLAGS) $(INCLUDES) -o $(MAIN) $(OBJS)

.PRECIOUS: %.o

.c.o:
        $(CC) $(CFLAGS) $(INCLUDES) -cpp $<  -o $@

clean:
        $(RM) *.o *~ $(MAIN)

depend: $(SRCS)
        makedepend $(INCLUDES) $^

我收到错误：

main.cpp:21:10: fatal error: 'mysql_connection.h' file not found
#include <mysql_connection.h>

如何为每个.o 添加包含？ tinyxml2 不使用 MySQL 连接器，所以我不应该添加 -lmysqlcppconn。怎么做？

Answer 1

您可以逐步构建生成文件。从 build 命令开始，使其成为 makefile 目标（我删除了-stdlib=libc++）：

app.cgi: main.cpp
    g++ -o app.cgi -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc -L/usr/local/mysql-connector-c++/lib64 main.cpp -lmysqlcppconn

接下来您可以将大部分元素提取到变量中并添加编译器标志：

CXX = g++
CXXFLAGS = -Wall -g -std=c++11
MAIN = app.cgi
CPPFLAGS = -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc
SRCS = main.cpp
LDFLAGS = -L/usr/local/mysql-connector-c++/lib64
LDLIBS = -lmysqlcppconn

$(MAIN): $(SRCS)
    $(CXX) $(CXXFLAGS) $(CPPFLAGS) -o $(MAIN) $(SRCS) $(LDFLAGS) $(LDLIBS)

添加一个clean 和一个all 目标：

CXX = g++
CXXFLAGS = -Wall -g -std=c++11
MAIN = app.cgi
CPPFLAGS = -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc
SRCS = main.cpp
LDFLAGS = -L/usr/local/mysql-connector-c++/lib64
LDLIBS = -lmysqlcppconn

.PHONY: all clean

all:    $(MAIN)

$(MAIN): $(SRCS)
    $(CXX) $(CXXFLAGS) $(CPPFLAGS) -o $(MAIN) $(SRCS) $(LDFLAGS) $(LDLIBS)

clean:
    $(RM) *.o *~ $(MAIN)

分为编译器步骤（隐式makefile规则）和链接器步骤：

CXX = g++
CXXFLAGS = -Wall -g -std=c++11
MAIN = app.cgi
CPPFLAGS = -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc
SRCS = main.cpp
OBJS = $(SRCS:.cpp=.o)
LDFLAGS = -L/usr/local/mysql-connector-c++/lib64
LDLIBS = -lmysqlcppconn

.PHONY: all clean

all:    $(MAIN)

$(MAIN): $(OBJS)
    $(CXX) -o $(MAIN) $(OBJS) $(LDFLAGS) $(LDLIBS)

clean:
    $(RM) *.o *~ $(MAIN)

最后加上./tinyxml2/tinyxml2.cpp：

CXX = g++
CXXFLAGS = -Wall -g -std=c++11
MAIN = app.cgi
CPPFLAGS = -I/usr/local/include -I/usr/local/mysql-connector-c++-8.0.21/include/jdbc
SRCS = main.cpp ./tinyxml2/tinyxml2.cpp
OBJS = $(SRCS:.cpp=.o)
LDFLAGS = -L/usr/local/mysql-connector-c++/lib64
LDLIBS = -lmysqlcppconn

.PHONY: all clean

all:    $(MAIN)

$(MAIN): $(OBJS)
    $(CXX) -o $(MAIN) $(OBJS) $(LDFLAGS) $(LDLIBS)

clean:
    $(RM) *.o *~ $(MAIN)