boost : Just iterate over elements of a ptree

Question

This should be simple (I'm just learning boost so I'm missing something)

I have read in some simple JSON using json_read and now have a ptree. All the examples on the web show using ptree.get("entry_name") to obtain an entry. All I want to do is something like:

 ptree pt;
 read_json(ss,pt);

 BOOST_FOREACH(ptree::value_type &v, pt)
 {
   std::cout << v.{entry_name} << v.{value}
 }

i.e. loop through the ptree and write out each name (i.e. what you put into pt.get()) and it's corresponding value.

Sorry if this is simple

Ross

Answer 1

I was searching the same thing, and couldn't find the answer anywhere. It turned out to be pretty simple indeed:

ptree pt;
/* load/fill pt */
for(iterator iter = pt.begin(); iter != pt.end(); iter++)
{
  std::cout << iter->first << "," << iter->second.data() << std::endl;
}

iter->first is the entry name, and iter->second.data() is the entry value of the first level. (You can then re-iterate with iter->second.begin()/end() for deeper levels.)

Further, if one such node in this iteration is not a terminal node and is itself a ptree, you can get that as ptree from this iterator itself : ptree subPt = iter->second.get_child("nodeName");