Author：张继飞

插入节点部分的实现是从现有节点的后面添加。

为了解决插入后不对齐的问题，需要修改这几个地方

doc=xmlParseFile("xml.xml"); 改为    doc=xmlReadFile("xml.xml","UTF-8",XML_PARSE_NOBLANKS);

xmlSaveFormatFile("xml.xml", doc, 0); 改为 xmlSaveFormatFile("xml.xml", doc, 1);

#include <stdio.h>
#include <stdlib.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
int main(int argc, char **argv)
{///insert message into xml.xml 该部分为在相关xml文件插入节点
    xmlDocPtr doc = NULL;       /* document pointer */
    xmlNodePtr root_node = NULL, node = NULL, node1 = NULL;/* node pointers */
    doc=xmlParseFile("xml.xml");          //首先解析xml文件，放入内存
    root_node = xmlDocGetRootElement(doc);     //获取根节点
//creates a new node, which is "attached" as child node of root_node node. 
    node = xmlNewChild(root_node, NULL, BAD_CAST "node1",BAD_CAST "content of node1");   //根据根节点(root_node)来插入根节点的的子节点为node1，
           xmlNewChild(node, NULL, BAD_CAST "node2",BAD_CAST "node2 is node1's sub");    //根据子节点node1(node)来插入子节点的的子节点为node2，

node=xmlNewChild(root_node, NULL, BAD_CAST "node3",BAD_CAST"node has attributes"); //插入根节点的子节点node3
    xmlNewProp(node, BAD_CAST "attribute", BAD_CAST "yes");   //添加子节点的属性。
//Here goes another way to create nodes.
    node = xmlNewNode(NULL, BAD_CAST "node4");
    node1 = xmlNewText(BAD_CAST"other way to create content");
    xmlAddChild(node, node1);
    xmlAddChild(root_node, node); //Dumping document to stdio or file
    xmlSaveFormatFile("xml.xml", doc, 0);   //将此内存保存到文件

xmlFreeDoc(doc); /*free the document */
    xmlCleanupParser();
    xmlMemoryDump();//debug memory for regression tests
    return(0);
}
/*
int main(int argc, char **argv)
{///creat xml doc   该部分为创建xml文件
    xmlDocPtr doc = NULL;       // document pointer
    xmlNodePtr root_node = NULL, node = NULL, node1 = NULL;// node pointers
// Creates a new document, a node and set it as a root node
    doc = xmlNewDoc(BAD_CAST "1.0");
    root_node = xmlNewNode(NULL, BAD_CAST "root");
    xmlDocSetRootElement(doc, root_node);
//creates a new node, which is "attached" as child node of root_node node. 
    xmlNewChild(root_node, NULL, BAD_CAST "node1",BAD_CAST "content of node1");
// xmlNewProp() creates attributes, which is "attached" to an node.
    node=xmlNewChild(root_node, NULL, BAD_CAST "node3",BAD_CAST"node has attributes");
    xmlNewProp(node, BAD_CAST "attribute", BAD_CAST "yes");
//Here goes another way to create nodes.
    node = xmlNewNode(NULL, BAD_CAST "node4");
    node1 = xmlNewText(BAD_CAST"other way to create content");
    xmlAddChild(node, node1);
    xmlAddChild(root_node, node); //Dumping document to stdio or file
    xmlSaveFormatFileEnc(argc > 1 ? argv[1] : "-", doc, "UTF-8", 1);  //free the document
    xmlFreeDoc(doc);
    xmlCleanupParser();
    xmlMemoryDump();//debug memory for regression tests
    return(0);
}*/
/*
gcc -o main xml.c -lxml2 -I /usr/include/libxml2/

下面为创建后产生的结果：

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <node1>content of node1</node1>
  <node3 attribute="yes">node has attributes</node3>
  <node4>other way to create content</node4>
</root>

下面为在上面基础上执行插入后产生的结果，虽然后面的排列不整齐，但不影响xml的解析。

<?xml version="1.0" encoding="UTF-8"?>
<root>
 <node1>content of node1</node1>
 <node3 attribute="yes">node has attributes</node3>
 <node4>other way to create content</node4>
<node1>content of node1</node1><node3 attribute="yes">node has attributes</node3><node4>other way to create content</node4><node1>content of node1<node2>node2 is node1's sub</node2></node1><node3 attribute="yes">node has attributes</node3><node4>other way to create content</node4></root>

*/