How to erase a value from the inner map, in a map of maps in C++

Question

In the below example, I'd like to delete just t and keep rest of the values associated with id.

std::map<int,map<int,Object&>> rootSet;
rootSet.erase(id,t);

Answer 1

The erase function cannot do this. You would have to do this yourself by grabbing a reference to the inner map, and calling erase on it.

std::map<int,std::map<int,Object&>> rootSet;
auto _where = rootSet.find(id);
if ( _where != rootSet.end() ) {
    _where->second.erase( t );
}