C++: Trouble with Parsing XML using Libxml - c++

Question

I am having a lot of trouble working with the libxml2 library to parse an xml file.
I have weeded out a previous, similar problem, but have run into another.
Here is the problem code:
class SSystem{
public:
//Constructors
SSystem(){};
//Make SSystem from XML Definition. Pass ptr to node
SSystem(xmlNodePtr Nptr, xmlDocPtr Dptr){
name = wxString((char *)xmlGetProp(Nptr, (xmlChar*)"name"), wxConvUTF8);
//Move to next level down, the <general> element
Nptr = Nptr->xmlChildrenNode;
//Move one more level down to the <radius> element
Nptr = Nptr->xmlChildrenNode;
//Get Radius value
if (!xmlStrcmp(Nptr->name, (const xmlChar *)"radius")) {
char* contents = (char*)xmlNodeGetContent(Nptr);
std::string test1 = std::string(contents);
radius = wxString(contents, wxConvUTF8);
}
}
Both an xmlNodePtr and an xmlDocPtr are passed to the constructor, which works fine taking just a property ("name"), but is now choking on further parsing.
Here is a piece of the xml file in question:
<?xml version="1.0" encoding="UTF-8"?>
<Systems>
<ssys name="Acheron">
<general>
<radius>3500.000000</radius> <-- I am trying to get this value (3500).
<stars>300</stars>
<asteroids>0</asteroids>
<interference>0.000000</interference>
<nebula volatility="0.000000">0.000000</nebula>
</general>
It compiles fine, but crashes when the constructor is loaded (I know because, if I comment out the if conditional and the char* contents = (char*)xmlNodeGetContent(Nptr->xmlChildrenNode), it runs fine.
I've tried so many different things (removed one of the Nptr->xmlChildrenNode), but nothing works.
What is wrong?

Answer 1

This:
char* contents = (char*)xmlNodeGetContent(Nptr->xmlChildrenNode)
Should probably be this:
char* contents = (char*)xmlNodeGetContent(Nptr)

Answer 2

Okay, I am going to use a different XML parsing library, as Libxml is a bit too complicated for me.
I am looking into using MiniXML (http://www.minixml.org/).

Answer 3

#Biosci3c:
The method you are calling returns some fake value. You should not call the method
char*)xmlNodeGetContent(Nptr->xmlChildrenNode)
instead you have to get the data corresponding to radius in cdata callback method below here.
void cdataBlock (void * ctx,
const xmlChar * value,
int len)
Check out in libxml library documentation for reference...

Answer 4

I just wrote a C++ wrapper to libxml2. It is on github if someone is interested: https://github.com/filipenf/libxml-cpp-wrapper
The idea is to make the use of libxml2 easier for C++ programmers - that's the main goal of this wrapper.
In the github repository there is a simple example of how to use it, but you can use it like this:
string office_phone = reader.getNodes()[0]["Customer"]["ContactInfo"]["OfficePhone"].text;
It is a work-in-progress so there is many room for improvement....