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(C++) boost::property_tree example 1: read and write


boost::property_tree example 1: read and write.







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Qt project file: CppProperty_treeExample1.pro


# Project created by QtCreator 2011-08-13T07:58:58
QT       += core
QT       -= gui
TARGET = CppProperty_treeExample1
CONFIG   += console
CONFIG   -= app_bundle
SOURCES += main.cpp








// ----------------------------------------------------------------------------
// Copyright (C) 2002-2006 Marcin Kalicinski
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// For more information, see www.boost.org
// ----------------------------------------------------------------------------

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/xml_parser.hpp>
//#include <boost/foreach.hpp>
#include <string>
#include <set>
#include <exception>
#include <iostream>

struct debug_settings
    std::string m_file;               // log filename
    int m_level;                      // debug level
    std::set<std::string> m_modules;  // modules where logging is enabled
    void load(const std::string &filename);
    void save(const std::string &filename);

void debug_settings::load(const std::string &filename)

    // Create empty property tree object
    using boost::property_tree::ptree;
    ptree pt;

    // Load XML file and put its contents in property tree.
    // No namespace qualification is needed, because of Koenig
    // lookup on the second argument. If reading fails, exception
    // is thrown.
    read_xml(filename, pt);

    // Get filename and store it in m_file variable. Note that
    // we specify a path to the value using notation where keys
    // are separated with dots (different separator may be used
    // if keys themselves contain dots). If debug.filename key is
    // not found, exception is thrown.
    m_file = pt.get<std::string>("debug.filename");

    // Get debug level and store it in m_level variable. This is
    // another version of get method: if debug.level key is not
    // found, it will return default value (specified by second
    // parameter) instead of throwing. Type of the value extracted
    // is determined by type of second parameter, so we can simply
    // write get(...) instead of get<int>(...).
    m_level = pt.get("debug.level", 0);

    // Iterate over debug.modules section and store all found
    // modules in m_modules set. get_child() function returns a
    // reference to child at specified path; if there is no such
    // child, it throws. Property tree iterator can be used in
    // the same way as standard container iterator. Category
    // is bidirectional_iterator.
    //BOOST_FOREACH(ptree::value_type &v, pt.get_child("debug.modules"))
    //    m_modules.insert(v.second.data());


void debug_settings::save(const std::string &filename)

    // Create empty property tree object
    using boost::property_tree::ptree;
    ptree pt;

    // Put log filename in property tree
    pt.put("debug.filename", m_file);

    // Put debug level in property tree
    pt.put("debug.level", m_level);

    // Iterate over modules in set and put them in property
    // tree. Note that put function places new key at the
    // end of list of keys. This is fine in most of the
    // situations. If you want to place item at some other
    // place (i.e. at front or somewhere in the middle),
    // this can be achieved using combination of insert
    // and put_value functions
    //BOOST_FOREACH(const std::string &name, m_modules)
    //    pt.put("debug.modules.module", name, true);

    // Write property tree to XML file
    write_xml(filename, pt);


int main()
        debug_settings ds;
        std::cout << "Success\n";
    catch (std::exception &e)
        std::cout << "Error: " << e.what() << "\n";
    return 0;






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