XML parsing with PugiXML, infinite loop

Question

this is pretty much the first C++ program that I ever made, it should display a list of xml nodes in the document. I made an exact same thing work using TinyXML, but I find Pugi much nicer and would like to continue using it.

Program code:

#include <iostream>
#include <string>
#include <vector>
using namespace std;


#include "pugixml/src/pugixml.hpp"
#include "pugixml/src/pugiconfig.hpp"
#include "pugixml/src/pugixml.cpp"
using namespace pugi;

const char * identify(xml_node node)
{
    const char * type;
    switch(node.type())
    {
        case node_null:
            type = "Null";
            break;
        case node_document:
            type = "Document";
            break;
        case node_element:
            type = "Element";
            break;
        case node_pcdata:
            type = "PCDATA";
            break;
        case node_cdata:
            type = "CDATA";
            break;
        case node_comment:
            type = "Comment";
            break;
        case node_pi:
            type = "Pi";
            break;
        case node_declaration:
            type = "Declaration";
            break;
        case node_doctype:
            type = "Doctype";
            break;
        default:
            type = "Invalid";
    }
    return type;
}

void walk(xml_node parent)
{
    printf("%s:\t%s\t%s\n", identify(parent), parent.name(), parent.value());
    for(xml_node child = parent.first_child(); child != 0; child = parent.next_sibling())
    {
        walk(child);
    }
}

int main(int argc, char* argv[])
{
    for (int i=1; i<argc; i++)
    {
        xml_document doc;
        xml_parse_result result = doc.load_file(argv[i]);

        cout << argv[i] << ": " << result.description() << endl;

        if (result)
        {
            walk(doc);
        }
    }

    return 0;
}

Sample XML:

<?xml version="1.0" encoding="iso-8859-1" standalone="yes"?> 
<iOne>
    <iTwo>
        <iThree>
            <one>1</one>
            <two>2</two>
            <three>3</three>
        </iThree>
    </iTwo>

    <one>1</one>
    <two>2</two>
    <three>3</three>

</iOne>

The code works until it comes across the first of the two <three>s and goes into an infinite loop, which mades me think there is something wrong with condition in for(xml_node child = parent.first_child(); child != 0; child = parent.next_sibling()) but everything is the same as in examples? I probably missed something pretty obvious... these are my first baby steps in c++ though :)

I am given to understand NULL in C++ is just 0 right?

Also (sorry for asking multiple questions), is this really a correct way of doing stuff with pugi? For a C++ program, I dont seem to be using pointers much? Im confused.

Mat · Accepted Answer · 2011-05-18 15:18:24Z

5

Have you tried changing that for loop to:

for(xml_node child = parent.first_child(); child; child = child.next_sibling())

This is how the samples do it (traverse_base.cpp for example).

The important part is child = child.next_sibling(), not parent.next_sibling().

edited May 18, 2011 at 15:18

answered May 18, 2011 at 15:05

Mat

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3 Comments

Dreen Over a year ago

Yeah, that is what I actually had originally, it still goes into infinite loop.

Mat Over a year ago

updated my answer - I think that's more likely than the previous thing I mentionned.

Sin Han Jinn Over a year ago

The "important part" help save me more hours of searching for the problem. Thanks @Mat

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