使用rapidxml操作xml~读写文件操作

rapidxml~网上很容易下，下面介绍使用方法：

1、xml写文件
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文件为:

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

2、读xml文件

基本的步骤为
首先获取xml文件数据
然后分析数据
获取节点
获取属性
获取名字
获取值
...

代码如下:

#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;
     
     //! 获取根节点
      xml_node<>* root = doc.first_node();
      std::cout<<root->name()<<std::endl;

     //! 获取根节点第一个节点
      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;
     
     //! 修改之后再次保存
      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为:

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 >

需要说明的是rapidxml明显有一个bug
那就是append_node(doc.allocate_node(node_element,"h","0"));的时候并不考虑该对象是否存在!