how to print std::set of std::maps - c++

Question

Here is the map with a string key and a structure value
1. Firstly I am creating a map of integer and a structure as value
std::map<int,struct value>; and then I am adding all these map objects to a set
std::set<std::map<int,struct value>> and I would like to understand how to loop through this set
I am not able to access the maps that are the part of this set, please suggest
struct values
{
std::string a;
std::string b;
values():a("milepost"),b("dummyval"){};
values( std::string ab, std::string bc)
{
a=ab;
b=bc;
};
bool operator<(const values& other) const {
return (a< other.a && b < other.b) ;
}
friend std::ostream& operator<<(std::ostream& os, const values& val);
};
std::ostream& operator<< (std::ostream& os , const values& val)
{
os << val.a <<"\t"<< val.b;
return os;
}
typedef std::map<std::string,values> myWsData;
main()
{
values a;
myWsData et_Data1,pt_Data2;
et_Data2.insert(std::make_pair("780256", a));
pt_Data2.insert(std::make_pair("780256", a));
std::set<myWsData> myet_pt_data;
myet_pt_data.insert(et_Data1);
myet_pt_data.insert(pt_Data2);
for (auto &i:myet_pt_data)
{
std::cout<<i<<"\n";
}
}

Answer 1

You have to use two loops, like so:
for (auto const& it1 : myet_pt_data)
{
for (auto const& it2 : it1)
{
std::cout << it2.first << '\t' << it2.second << std::endl;
}
}
When you use auto const& in your range-based for loops you avoid copying the set and all its content.
The types are as follows:
decltype(it1) is std::map<std::string,values> const&, and
decltype(it2) is std::pair<std::string const,values> const&
For completeness, note that the std::string in it2 (the std::pair) is const.

Answer 2

How about this:
#include <iostream>
#include <map>
#include <set>
#include <algorithm>
using namespace std;
int main(int argc, char *argv[])
{
set<map<int,string> > list;
//fill list
std::for_each(list.begin(), list.end(), [](auto set_el){
std::for_each(set_el.begin(),set_el.end(),[](auto map_el) {
std::cout<<map_el.first<<"\t"<<map_el.second<<std::endl;
});
});
cout << "Hello World!" << endl;
return 0;
}

Answer 3

You are probably missing a inner loop:
// iterates through all elements of the set:
for (const auto& the_map : myet_pt_data)
{
// the_map takes all values from the set
// the_map actual type is const std::map<std::string,values>&
for (const auto& the_value : the_map)
{
// the_value takes all value of the current map (the_map)
// the_value actual type is const std::pair<std::string,values>&
std::cout << the_value.first << " value is " << the_value.second << std::endl;
}
}