How to parse ini file with Boost

Question

I have a ini file which contains some sample values like:

[Section1] Value1 = 10 Value2 = a_text_string 

I'm trying to load these values and print them in my application with Boost but I don't understand how to do this in C++.

I searched in this forum in order to find some examples (I always used C and so I'm not very good in C++) but I found only examples about how to read values from file all at once.

I need to load just a single value when I want, like string = Section1.Value2 because I don't need to read all the values, but just few of them.

I'd like to load single values and to store them in variable in order to use them when I want in my application.

It is possible to do this with Boost?

At the moment, I'm using this code:

#include <iostream> #include <string> #include <set> #include <sstream> #include <exception> #include <fstream> #include <boost/config.hpp> #include <boost/program_options/detail/config_file.hpp> #include <boost/program_options/parsers.hpp>  namespace pod = boost::program_options::detail;  int main() {    std::ifstream s("file.ini");     if(!s)     {         std::cerr<<"error"<<std::endl;         return 1;     }      std::set<std::string> options;     options.insert("Test.a");     options.insert("Test.b");     options.insert("Test.c");      for (boost::program_options::detail::config_file_iterator i(s, options), e ; i != e; ++i)         std::cout << i->value[0] << std::endl;    } 

But this just read all the values in a for loop; at the contrary I just want to read single values when I want and I don't need to insert values in the file, because it is already written with all the values which I need in my program.

Answer 1

You can also use Boost.PropertyTree to read .ini files:

#include <boost/property_tree/ptree.hpp> #include <boost/property_tree/ini_parser.hpp>  ...  boost::property_tree::ptree pt; boost::property_tree::ini_parser::read_ini("config.ini", pt); std::cout << pt.get<std::string>("Section1.Value1") << std::endl; std::cout << pt.get<std::string>("Section1.Value2") << std::endl;