Boost解析xml——xml写入

<?xml version="1.0" encoding="utf-8"?>
<Config>
    <Item name="IP测试报告2017-10-24 09-54-31">
        <ChildItem name="Date" desc="" datatype ="string">2017-10-24 09-54-31</ChildItem>
        <ChildItem name="FailureCount" desc="" datatype ="int">1</ChildItem>
        <ChildItem name="IPAddressCount" desc="" datatype ="int">4</ChildItem>
        <ChildItem name="SuccessCount" desc="" datatype ="int">3</ChildItem>
    </Item>
</Config>

如何生成以上xml

  for (map<wstring, map<wstring, HistoryData>>::iterator it = vect_str.begin(); it != vect_str.end(); it++)
        { //迭代vector  
            for (map<wstring, HistoryData>::iterator it1 = it->second.begin(); it1 != it->second.end(); it1++)
            {
                m_pt3.add(L"<xmlattr>.name", it1->second.name);
                m_pt3.add(L"<xmlattr>.desc", it1->second.desc);
                m_pt3.add(L"<xmlattr>.datatype ", it1->second.datatype);
                m_pt3.put_value(it1->second.value);          
                m_pt2.add_child(L"ChildItem", m_pt3);  
                m_pt3.clear();
            }
            
            m_pt1.add_child(L"Item", m_pt2);
            m_pt1.add(L"Item.<xmlattr>.name", it->first);
            m_pt2.clear();
        }
        m_pt.add_child(L"Config", m_pt1);   
    auto settings = boost::property_tree::xml_writer_make_settings<std::wstring>(L'	', 1);
    write_xml(fileName, m_pt, utf8Locale, settings);   

如何在现有的xml里插入新的Item如下

<?xml version="1.0" encoding="utf-8"?>
<Config>
    <Item name="IP测试报告2017-10-24 09-54-31">
        <ChildItem name="Date" desc="" datatype="string">2017-10-24 09-54-31</ChildItem>
        <ChildItem name="FailureCount" desc="" datatype="int">1</ChildItem>
        <ChildItem name="IPAddressCount" desc="" datatype="int">4</ChildItem>
        <ChildItem name="SuccessCount" desc="" datatype="int">3</ChildItem>
    </Item>
    <Item name="IP测试报告2017-10-24 09-54-32">
        <ChildItem name="Date" desc="" datatype ="string">2017-10-24 09-54-32</ChildItem>
        <ChildItem name="FailureCount" desc="" datatype ="int">1</ChildItem>
        <ChildItem name="IPAddressCount" desc="" datatype ="int">4</ChildItem>
        <ChildItem name="SuccessCount" desc="" datatype ="int">3</ChildItem>
    </Item>
</Config>

代码

 if (auto firstChild = m_pt.get_child_optional(L"Config"))
    {
        m_pt4 = m_pt.get_child(L"Config");
        m_pt.clear();
        for (map<wstring, map<wstring, HistoryData>>::iterator it = vect_str.begin(); it != vect_str.end(); it++)
        { //迭代vector  
            for (map<wstring, HistoryData>::iterator it1 = it->second.begin(); it1 != it->second.end(); it1++)
            {
                m_pt3.add(L"<xmlattr>.name", it1->second.name);
                m_pt3.add(L"<xmlattr>.desc", it1->second.desc);
                m_pt3.add(L"<xmlattr>.datatype ", it1->second.datatype);
                m_pt3.put_value(it1->second.value);
                m_pt2.add_child(L"ChildItem", m_pt3)；
                m_pt3.clear();
            }
            m_pt2.add(L"<xmlattr>.name", it->first);
            m_pt4.add_child(L"Item", m_pt2);
            m_pt2.clear();
        } 
        m_pt.add_child(L"Config", m_pt4);
    }
    else
    {
        for (map<wstring, map<wstring, HistoryData>>::iterator it = vect_str.begin(); it != vect_str.end(); it++)
        { //迭代vector  
            for (map<wstring, HistoryData>::iterator it1 = it->second.begin(); it1 != it->second.end(); it1++)
            {
                m_pt3.add(L"<xmlattr>.name", it1->second.name);
                m_pt3.add(L"<xmlattr>.desc", it1->second.desc);
                m_pt3.add(L"<xmlattr>.datatype ", it1->second.datatype);
                m_pt3.put_value(it1->second.value);         
                m_pt2.add_child(L"ChildItem", m_pt3);
                m_pt3.clear();
            }
            m_pt1.add_child(L"Item", m_pt2);
            m_pt1.add(L"Item.<xmlattr>.name", it->first);
            m_pt2.clear();
        }
        m_pt.add_child(L"Config", m_pt1);      
    }
    auto settings = boost::property_tree::xml_writer_make_settings<std::wstring>(L'	', 1);
    write_xml(fileName, m_pt, utf8Locale, settings);