使用rapidxml操作xml~讀寫文件操作

rapidxml~網上很容易下，下面介紹使用方法：

1、xml寫文件
如下:

#include <iostream>
#include <rapidxml/rapidxml.hpp>
#include <rapidxml/rapidxml_utils.hpp>
#include <rapidxml/rapidxml_print.hpp>

using namespace rapidxml;

int main()
{    
      xml_document<> doc;  
      xml_node<>* rot = doc.allocate_node(rapidxml::node_pi,doc.allocate_string("xml version='1.0' encoding='utf-8'"));
      doc.append_node(rot);
      xml_node<>* node =   doc.allocate_node(node_element,"config","information");  
      xml_node<>* color =   doc.allocate_node(node_element,"color",NULL);  
      doc.append_node(node);
      node->append_node(color);
      color->append_node(doc.allocate_node(node_element,"red","0.1"));
      color->append_node(doc.allocate_node(node_element,"green","0.1"));
      color->append_node(doc.allocate_node(node_element,"blue","0.1"));
      color->append_node(doc.allocate_node(node_element,"alpha","1.0"));

      xml_node<>* size =   doc.allocate_node(node_element,"size",NULL); 
      size->append_node(doc.allocate_node(node_element,"x","640"));
      size->append_node(doc.allocate_node(node_element,"y","480"));
      node->append_node(size);

      xml_node<>* mode = doc.allocate_node(rapidxml::node_element,"mode","screen mode");
      mode->append_attribute(doc.allocate_attribute("fullscreen","false"));
      node->append_node(mode);

      std::string text;  
      rapidxml::print(std::back_inserter(text), doc, 0);  

      std::cout<<text<<std::endl; 
    
      std::ofstream out("config.xml");
     out << doc;

      system("PAUSE");
     return EXIT_SUCCESS;
}

生成的xml文件爲:

<?xml version='1.0' encoding='utf-8' ?>
<config>
    <color>
        <red>0.1</red>
        <green>0.1</green>
        <blue>0.1</blue>
        <alpha>1.0</alpha>
    </color>
    <size>
        <x>640</x>
        <y>480</y>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>

2、讀xml文件

基本的步驟爲
首先獲取xml文件數據
然後分析數據
獲取節點
獲取屬性
獲取名字
獲取值
...

代碼如下:

#include <iostream>
#include <rapidxml/rapidxml.hpp>
#include <rapidxml/rapidxml_utils.hpp>
#include <rapidxml/rapidxml_print.hpp>
 
using namespace rapidxml;

int main()
{    
      file<> fdoc("config.xml");
      std::cout<<fdoc.data()<<std::endl; 
      xml_document<>   doc;    
      doc.parse<0>(fdoc.data()); 

      std::cout<<doc.name()<<std::endl;
     
     //! 獲取根節點
      xml_node<>* root = doc.first_node();
      std::cout<<root->name()<<std::endl;

     //! 獲取根節點第一個節點
      xml_node<>* node1 = root->first_node();
      std::cout<<node1->name()<<std::endl; 

      xml_node<>* node11 = node1->first_node();
      std::cout<<node11->name()<<std::endl;
      std::cout<<node11->value()<<std::endl;
     
     //! 修改之後再次保存
      xml_node<>* size = root->first_node("size");
      size->append_node(doc.allocate_node(node_element,"w","0"));
      size->append_node(doc.allocate_node(node_element,"h","0"));

      std::string text;  
      rapidxml::print(std::back_inserter(text),doc,0);  
 
      std::cout<<text<<std::endl; 
    
      std::ofstream out("config.xml");
     out << doc;

      system("PAUSE");
     return EXIT_SUCCESS;
}

生成的xml爲:

<?xml version='1.0' encoding='utf-8' ?>
<config>
    <color>
        <red>0.1</red>
        <green>0.1</green>
        <blue>0.1</blue>
        <alpha>1.0</alpha>
    </color>
    <size>
        <x>640</x>
        <y>480</y>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>

需要說明的是rapidxml明顯有一個bug
那就是append_node(doc.allocate_node(node_element,"h","0"));的時候並不考慮該對象是否存在!