[ACCEPTED]-boost : Just iterate over elements of a ptree-boost-propertytree

Accepted answer

Score: 17

I was searching the same thing, and couldn't 8 find the answer anywhere. It turned out 7 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 6 name, and iter->second.data() is the entry value of the first 5 level. (You can then re-iterate with iter->second.begin()/end() for 4 deeper levels.)

Further, if one such node 3 in this iteration is not a terminal node 2 and is itself a ptree, you can get that 1 as ptree from this iterator itself : ptree subPt = iter->second.get_child("nodeName");

Score: 2

I'm having troubles with ptree as well, but 3 perhaps this can help: Check out boost's ptree quick tutorial

v.{entry_name}
would 2 be
v.first

and

v.{value}
v.second.data()

Would 1 that work?

Score: 1

Here's a great example of how to iterate 5 a ptree using BOOST_FOREACH http://akrzemi1.wordpress.com/2011/07/13/parsing-xml-with-boost/

for direct access 4 using the normal "get" functions 3 look at the example from boost: http://www.boost.org/doc/libs/1_51_0/doc/html/boost_propertytree/tutorial.html

the documentation 2 page is located here: http://www.boost.org/doc/libs/1_51_0/doc/html/boost/property_tree/basic_ptree.html I know its not very 1 well documented but it is helpful.

Score: 1

Old thread, but here's a C++11 version of 2 mr_georg's answer with range-based for loops:

ptree pt;
/* load/fill pt */
for(auto pair : pt)
{
  std::cout << pair.first << "," << pair.second.data() << std::endl;
}

For 1 this json:

{
    "key1":"value1",
    "key2":"value2"
}

It outputs:

key1,value1
key2,value2

Score: 0

This example iterates over a simple JSON 1 object and puts its values into a vector.

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <boost/lexical_cast.hpp>

#include <iostream>
#include <string>
#include <vector>
#include <sstream>

int main (void)
{   
    try
    {        
        std::stringstream ss;
        std::string json_obj_str = "{ \"unit_1\": 1, \"unit_2\": 2, \"unit_3\": 3 }";
        std::vector <float> fvec;

        ss << json_obj_str; // put string into stringstream

        boost::property_tree::ptree pt;
        boost::property_tree::read_json(ss, pt);    // put stringstream into property tree

        // iterate over JSON properties
        for (boost::property_tree::ptree::iterator iter = pt.begin(); iter != pt.end(); iter++)
        {
            std::cout << iter->first << ": " << iter->second.data() << std::endl;
            fvec.push_back(boost::lexical_cast<float>(iter->second.data()));
        }

        for (size_t i = 0; i < fvec.size(); i++)
        {
            std::cout << "fvec.at(" << i << ") = " << fvec.at(i) << std::endl;
        }
    }
    catch (const boost::property_tree::ptree_error &e)
    {
        std::cerr << "property_tree error = " << e.what() << std::endl;
        return -2;
    }       
    catch (std::exception const& e)
    {
        std::cerr << "exception = " << e.what() << std::endl;
        return -1;
    }

    return 0;
}

Source: stackoverflow.com

[ACCEPTED]-boost : Just iterate over elements of a ptree-boost-propertytree

How do I connect to a database and loop over a recordset in C#?

Java For-Each Loop : Sort order

To understand: From PHP Array to Python?

Using lock statement within a loop in C#

All elements of An ArrayList change when a new one is added?

How to update glut window continuously?

PHP while loop add by 2

How to add items to an array while looping through it?

Access to the next value in a Twig loop

Iterating over the array in random order