1

我是 XML 解析业务的新手。很抱歉提出愚蠢的问题。

我想浏览我的 XML：

<?xml version="1.0"?>
<catalog>
   <book id="bk101">
      <author>Gambardella, Matthew</author>
      <title>XML Developer's Guide</title>
      <genre>Computer</genre>
      <price>44.95</price>
      <publish_date>2000-10-01</publish_date>
      <description>An in-depth look at creating applications 
      with XML.</description>
   </book>
   <book id="bk102">
      <author>Ralls, Kim</author>
      <title>Midnight Rain</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2000-12-16</publish_date>
      <description>A former architect battles corporate zombies, 
      an evil sorceress, and her own childhood to become queen 
      of the world.</description>
   </book>
   <book id="bk103">
      <author>Corets, Eva</author>
      <title>Maeve Ascendant</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2000-11-17</publish_date>
      <description>After the collapse of a nanotechnology 
      society in England, the young survivors lay the 
      foundation for a new society.</description>
   </book>
   <book id="bk104">
      <author>Corets, Eva</author>
      <title>Oberon's Legacy</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2001-03-10</publish_date>
      <description>In post-apocalypse England, the mysterious 
      agent known only as Oberon helps to create a new life 
      for the inhabitants of London. Sequel to Maeve 
      Ascendant.</description>
   </book>
   <book id="bk105">
      <author>Corets, Eva</author>
      <title>The Sundered Grail</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date>2001-09-10</publish_date>
      <description>The two daughters of Maeve, half-sisters, 
      battle one another for control of England. Sequel to 
      Oberon's Legacy.</description>
   </book>
   <book id="bk106">
      <author>Randall, Cynthia</author>
      <title>Lover Birds</title>
      <genre>Romance</genre>
      <price>4.95</price>
      <publish_date>2000-09-02</publish_date>
      <description>When Carla meets Paul at an ornithology 
      conference, tempers fly as feathers get ruffled.</description>
   </book>
   <book id="bk107">
      <author>Thurman, Paula</author>
      <title>Splish Splash</title>
      <genre>Romance</genre>
      <price>4.95</price>
      <publish_date>2000-11-02</publish_date>
      <description>A deep sea diver finds true love twenty 
      thousand leagues beneath the sea.</description>
   </book>
   <book id="bk108">
      <author>Knorr, Stefan</author>
      <title>Creepy Crawlies</title>
      <genre>Horror</genre>
      <price>4.95</price>
      <publish_date>2000-12-06</publish_date>
      <description>An anthology of horror stories about roaches,
      centipedes, scorpions  and other insects.</description>
   </book>
</catalog>

而我试图运行的代码（按照互联网教程）是：

tinyxml2::XMLDocument mappedxml1;
XMLError eResult = mappedxml1.LoadFile(filename1);
if(eResult == XML_SUCCESS){
        printf("XMLERROR is %d\nXML loading successfull.\n",eResult);
    }
    else{
        printf("XMLERROR is %d\nXML loading unsuccessfull.\n",eResult);
    }
XMLNode * pRoot1 = mappedxml1.FirstChild();
    if(pRoot1 == NULL){printf("ERROR: NO ROOT\n");}
    else{printf("Good pointer\n");}
XMLElement * pbook1 = pRoot1->FirstChildElement("book id");
    if (pbook1 == NULL){printf("ERROR PARSING ELEMENT\n");}
    else{printf("GOT IT\n");}

虽然pRoot1很好，但价值pbook1始终是NULL。我希望它指向bk101

有什么帮助或建议吗？先感谢您

4

1 回答 1

6

您正在尝试查找名为book id. 没有这样的元素。

但是，有名称为book!的元素。
（并且每个都有一个名为的属性id。）

您还需要解析器跳过您的 XML 声明，该声明当前正在被FirstChild调用捕获（所以*pRoot1不是您认为的那样！）。你可以试试FirstChildElement("catalog")那里。

顺便说一句，我建议检查您的错误处理程序；目前，如果pRoot1是一个空指针，那么您将一条消息写入控制台，然后愉快地继续尝试取消引用该空指针。

于 2016-05-06T12:05:44.130 回答