Here is the problem, by default the STL libraries use the operator== method
for any given comparison.
So if you try to use a map like this:
map<xmlChar *, my_object> my_map;
it will compare the pointers themselves, and not the contents of the
pointers.
Its like saying:
xmlChar *a, *b;
if( a==b ) {
// do something
}
The previous code is not valid when normally operating on strings.
The workaround is to provide a comparator function to the map object, you
can use the following:
struct xmlCmp {
bool operator()(const xmlChar* s1, const xmlChar* s2) const {
return xmlStrcmp(s1, s2) < 0;
}
};
map<xmlChar *, my_object, xmlCmp> my_better_map;
That should solve your STL problems.
Thanks,
James Wert Jr.
[EMAIL PROTECTED]
|---------+---------------------------->
| | Daniel Veillard |
| | <[EMAIL PROTECTED]|
| | com> |
| | Sent by: |
| | [EMAIL PROTECTED]|
| | .org |
| | |
| | |
| | 05/25/2005 03:26 |
| | AM |
| | Please respond to|
| | veillard |
|---------+---------------------------->
>----------------------------------------------------------------------------------------------------------------------------------|
|
|
| To: Antti M�kinen <[EMAIL PROTECTED]>
|
| cc: [email protected]
|
| Subject: Re: [xml] Problems with xmlChar* as a key in STL Map
|
>----------------------------------------------------------------------------------------------------------------------------------|
On Wed, May 25, 2005 at 09:12:08AM +0300, Antti M�kinen wrote:
> If I compare the the acquired xmlChar* with another xmlChar*, which is
> created like...
>
> xmlChar* test = BAD_CAST "and";
>
> ...with xmlStrcmp, the result is that the strings are the same. This test
> string I can use for searching a certain key in STL Map and it works. Why
> is it, that the xmlChar* acquired with XPath from a node does not work
when
> trying to find a key in STL Map? Does that have something to do with
> encoding or what, or with the method that STL Map uses for comparing
> strings?
I'm a bit puzzled by your question. I do not know "STL Map", I have no
idea
if this may have an influence. All I can tell is:
- the xmlChar* string obtained from libxml2 is encoded in UTF-8
(UTF-8 encoding and ASCII encoding match for characters in the ASCII
range)
- the string may be deallocated if you free the document or if you
free the XPath object which was returned, I assume that's the
problem you're facing.
otherwise no idea.
Daniel
--
Daniel Veillard | Red Hat Desktop team http://redhat.com/
[EMAIL PROTECTED] | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
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