boost xml

<?xml version="1.0" encoding="GB2312"?>
<content>
  <title value="xxxx"/>
  <number>1234</number>
  <groups>
  	<class num="1" type="type1"/>
  	<class num="2" type="type2"/>
  	<class num="3" type="type3"/>
  </groups>
  <classes>
  	<name>first</name>
  	<name>second</name>
  	<name>third</name>
  </classes>
</content>

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/xml_parser.hpp>
#include <boost/foreach.hpp>
#include <boost/typeof/std/utility.hpp>
#include <string>
#include <map>
#include <set>
#include <exception>
#include <iostream>

struct TestConfig
{
	std::string title;
	int number;
	std::map<int, std::string> groups;
	std::set<std::string> classes;
	void load(const std::string& filename);
	void save(const std::string& filename);
};

void TestConfig::load(const std::string& filename)
{
	using boost::property_tree::ptree;
	ptree pt;
	read_xml(filename, pt, boost::property_tree::xml_parser::trim_whitespace);

	title = pt.get_child("content.title").get<std::string>("<xmlattr>.value");
	std::cout << title << std::endl;

	number = pt.get<int>("content.number");
	std::cout << number << std::endl;

	ptree &groups_node = pt.get_child("content.groups");
	BOOST_FOREACH(const ptree::value_type& vt, groups_node)
	{
		std::string num = vt.second.get<std::string>("<xmlattr>.num");
		std::string type = vt.second.get<std::string>("<xmlattr>.type");
		groups.insert(std::pair<int, std::string>(atoi(num.c_str()), type));
		std::cout << num << "," << type << std::endl;
	}

	ptree &classes_node = pt.get_child("content.classes");
	BOOST_FOREACH(const ptree::value_type& vt, classes_node)
	{
		classes.insert(vt.second.data());
		std::cout << vt.second.data() << std::endl;
	}
}

void TestConfig::save(const std::string& filename)
{
	using boost::property_tree::ptree;
	ptree pt, pattr1;

	pattr1.add<std::string>("<xmlattr>.value", title);
	pt.add_child("content.title", pattr1);
	pt.put("content.number", number);

	typedef std::map<int, std::string> map_type;
	BOOST_FOREACH(const map_type::value_type &grp, groups)
	{
		ptree pattr2;
		pattr2.add<int>("<xmlattr>.num", grp.first);
		pattr2.add<std::string>("<xmlattr>.type", grp.second);
		pt.add_child("content.groups.class", pattr2);
	}
	
	BOOST_FOREACH(const std::string& cls, classes)
	{
		pt.add("content.classes.name", cls);
	}
	
	// 格式化输出，指定编码（默认utf-8）
	boost::property_tree::xml_writer_settings<char> settings('\t', 1, "GB2312");
	write_xml(filename, pt, std::locale(), settings);
}


int main()
{
    try
    {
		TestConfig tc;
		tc.load("testConfigRead.xml");
		tc.save("testConfigWrite.xml");
        std::cout << "Success\n";
    }
    catch (std::exception &e)
    {
        std::cout << "Error: " << e.what() << "\n";
    }

	system("pause");
    return 0;
}