I'm trying to create a map inside a map:
typedef map<float,mytype> inner_map;
typedef map<float,inner_map> outer_map;
Will I be able to put something inside inner map, or does iterator::second returns a copy?
stl_pair.h suggests the latter:
74: _T2 second; ///< @c second is a copy of the second object
but my test program run fine with the code like this:
it = my_map.lower_bound(3.1415);
(*it).second.insert(inner_map::value_type(2.71828,"Hello world!");
So where is the truth? Is this a copy or not?
The comment in stl_pair.h
is misleading in this specific case.
There will be no copy, since the map::iterator
actually refers to the original data inside the map (the value_type
, which itself is a pair
), it’s not a copy. Thus iterator::second
also refers to the original data.