RapidXML节点异常处理

Question

I'm using RapidXML to parse a xml file containing some variables that I'd like to use in my C++ program. I am abled to read valid nodes but I'd like to add some error handling if a node name is misspelled for example.

Here is a working example of my files.

.cpp

try
{
    rapidxml::file<> xmlFile("file.xml");
    rapidxml::xml_document<> doc;
    doc.parse<parse_declaration_node | parse_no_data_nodes>(xmlFile.data());

    xml_node<>* prop_node = doc.first_node("PropertyList");
}
catch (const runtime_error& e)
{
    // Do something
}
catch (const rapidxml::parse_error& e)
{
    // Do something
}
catch (const exception& e)
{
    // Do something
}
catch(...)
{
    // Do something
}

.xml

<?xml version="1.0" encoding="utf-8"?>

<PropertyList>
    ...
</PropertyList>

If i however change the first_node() call in my .cpp file to a node that doesn't exists, like so:

xml_node<>* prop_node = doc.first_node("Property");

The program crashed in run time complaining about bad memory access instead of throwing an exception.

Is this the way RapidXML is supposed to work or am I doing something wrong?

Thanks!

Answer 1

I'm not entirely familiar with RapidXML, but I found from its reference page the following about first_node. http://rapidxml.sourceforge.net/manual.html#namespacerapidxml_1what_is_rapidxml

function xml_node::first_node

Synopsis

xml_node* first_node(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; Description

Gets first child node, optionally matching node name. Parameters

name Name of child to find, or 0 to return first child regardless of its name; this string doesn't have to be zero-terminated if name_size is non-zero name_size Size of name, in characters, or 0 to have size calculated automatically from string case_sensitive Should name comparison be case-sensitive; non case-sensitive comparison works properly only for ASCII characters Returns

Pointer to found child, or 0 if not found.

So you can either call first_node without having to specifying its name.(Although this might not be a direct answer to your problem.)

Or check if the return value of doc.first_node("Property") is 0. And only assign the value to prop_node if the return value is not 0.