ubuntu 中使用makefile组织c++多文件的简陋方法

现有类定义Sales_item.hpp Sales_item.cpp

主函数my7_31.cpp（代码来源于c++primer 习题解答7_31）

希望使用makefile在Ubuntu中进行编译链接，生成可执行文件edit。

注：目的是了解makefile如何使用，这个makefile文件并不通用，只能体现makefile的基本功能

代码如下

Sales_item.hpp

#pragma once
#include <iostream>
#include <string>

class Sales_item
{
public:
	Sales_item() :units_sold(0), revenue(0.0){}
private:
	std::string isbn;
	unsigned int units_sold;
	double revenue;
public:

	bool same_isbn(const Sales_item & rhs)const;

	std::istream & input(std::istream & in);
	std::ostream & output(std::ostream & out)const;
	double avg_price() const;
};

Sales_item.cpp

#include "Sales_item.hpp"

bool Sales_item::same_isbn(const Sales_item & rhs) const
{
	return this->isbn==rhs.isbn;
}

std::istream & Sales_item::input(std::istream & in)
{
	double price;
	in >> isbn >> units_sold >> price;
	if (in)
	{
		revenue = units_sold*price;
	}
	else
	{
		units_sold = 0; revenue = 0.0;
	}
	return in;
	//TODO: insert return statement here
}

std::ostream & Sales_item::output(std::ostream & out) const
{
	out << isbn << "\t" << units_sold << "\t" << revenue<<"\t"<<avg_price();
	return out;
	//TODO: insert return statement here
}

double Sales_item::avg_price()const
{
	if (units_sold)
		return revenue / units_sold;
	else
	{
		return 0;
	}

}

my7_31.cpp

//main for read class Sales_item
#include <iostream>
#include "Sales_item.hpp"

using namespace std;

int main ()
{
	Sales_item item;
	cout << "enter some trasactions(Ctrl+z to end) :" << endl;
	while (item.input(cin))
	{
		cout << "the trnsaction teade is :" << endl;
		item.output(cout);
		cout << endl;
	}
	return 0;
}

makefile

参考：http://www.chinaunix.net/old_jh/23/408225.html

edit:my7_31.o Sales_item.o
	g++ -o edit my7_31.o Sales_item.o
Sales_item.o:Sales_item.cpp Sales_item.hpp
	g++ -c Sales_item.cpp
my7_31.o:my7_31.cpp Sales_item.hpp
	g++ -c my7_31.cpp
clean:

上面是原始版本

简洁版，依赖于make强大的自动推导功能，只需要给出相应的.h依赖项即可

edit:my7_31.o Sales_item.o
	g++ -o edit my7_31.o Sales_item.o
Sales_item.o: Sales_item.hpp

my7_31.o:Sales_item.hpp

clean: