First solution is Use range_based for loop, like:
Note: When range_expression’s type is std::map then a range_declaration’s type is std::pair.
for ( range_declaration : range_expression )
//loop_statement
Code 1:
typedef std::map<std::string, std::map<std::string, std::string>> StringToStringMap;
StringToStringMap my_map;
for(const auto &pair1 : my_map)
{
// Type of pair1 is std::pair<std::string, std::map<std::string, std::string>>
// pair1.first point to std::string (first key)
// pair1.second point to std::map<std::string, std::string> (inner map)
for(const auto &pair2 : pair1.second)
{
// pair2.first is the second(inner) key
// pair2.second is the value
}
}
The Second Solution:
Code 2
typedef std::map<std::string, std::string> StringMap;
typedef std::map<std::string, StringMap> StringToStringMap;
StringToStringMap my_map;
for(StringToStringMap::iterator it1 = my_map.begin(); it1 != my_map.end(); it1++)
{
// it1->first point to first key
// it2->second point to inner map
for(StringMap::iterator it2 = it1->second.begin(); it2 != it1->second.end(); it2++)
{
// it2->second point to value
// it2->first point to second(inner) key
}
}