c++ - 如何使用rapidxml C++填充.xml文档

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rapidxml - overwriting previous xml_nodes

(1个答案)


6年前关闭。




我正在尝试这样的事情，

#include "stdafx.h"
#include "rapidxml.hpp"
//#include "rapidxml_iterators.hpp"
#include "rapidxml_print.hpp"
#include "rapidxml_utils.hpp"
#include <iostream>
#include <stdio.h>

using namespace rapidxml;

int _tmain(int argc, _TCHAR* argv[])
{

    std::ofstream theFile ("trial.xml");
    xml_document<> doc;
    xml_node<>* decl = doc.allocate_node(node_declaration);
    decl->append_attribute(doc.allocate_attribute("version", "1.0"));
    decl->append_attribute(doc.allocate_attribute("encoding", "UTF-8"));
    doc.append_node(decl);
    xml_node<>* root = doc.allocate_node(node_element, "page");
    root->append_attribute(doc.allocate_attribute("xmlns", "http://ALTEC-Center.org/xsd/ocr-annotation-1-0.xsd"));
    root->append_attribute(doc.allocate_attribute("Number of lines", "10"));
    doc.append_node(root);
    for (int i = 0; i < 8; i++)
    {
        //char  buf1[8];
        //std::sprintf(buf1, "%d", i);
        xml_node<>* child = doc.allocate_node(node_element, "line");
        child->append_attribute(doc.allocate_attribute("Index",std::to_string(i).c_str()));
        root->append_node(child);

        for (int j = 0; j < 8; j++)
        {
            xml_node<>* child1 = doc.allocate_node(node_element, "word");
            child1->append_attribute(doc.allocate_attribute("Index",std::to_string(j).c_str()));
            child1->append_attribute(doc.allocate_attribute("x","0.0"));
            child1->append_attribute(doc.allocate_attribute("y","0.1"));
            child1->append_attribute(doc.allocate_attribute("width","0.2"));
            child1->append_attribute(doc.allocate_attribute("hight","0.3"));
            child1->append_attribute(doc.allocate_attribute("word","محمد"));
            child->append_node(child1);
        }
    }
    theFile << doc;
    theFile.close();
    doc.clear();

    return 0;
}

但是输出如下

<line Index=" ">
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
    <word Index=" " x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
</line>

并且我想“索引”属性=循环“i”和“j”的迭代器值，例如

<word Index="0" x="0.0" y="0.1" width="0.2" hight ="0.3" word="محمد"/> //j=0
<word Index="1" x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>  //j=1
<word Index="2" x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>
<word Index="3" x="0.0" y="0.1" width="0.2" hight="0.3" word="محمد"/>

等等。
在前面的示例中，我只是尝试直接使用loop参数，但是稍后我想用word[i][j]这样的属性填充属性，我该怎么做呢？

最佳答案

您遇到了最常见的Rapidxml问题之一:以这种方式构建XML文档时，RapidXML不会复制您提供的字符串数据，而只是存储指向它们的指针。 (这是使其快速发展的重要原因)。

所以当你使用这个

child->append_attribute(doc.allocate_attribute("Index",std::to_string(i).c_str()));

..它存储指向从to_string(i)返回的临时字符串的指针。该内存将被覆盖，因此您生成的XML文档将更改。

相反，您应该分配一个临时的RapidXml字符串来保存文本:

char * idxStr = doc.allocate_string(std::to_string(i).c_str());
child->append_attribute(doc.allocate_attribute("Index", idxStr));

除非您使用文字字符串(例如"0.3")，否则应始终执行此操作