duplicate key in map also sort elements like map?

Question

Hi

i had assumption that when duplicate key is inserted in map, value gets updated into map. Same doesn't happen in below code.

https://code.sololearn.com/cf85vGNiY96J

Please share your views on this as I thought values get updated

Answer 1

std::map::insert fails to insert a key if the key already exists.
It does not update the value if it does exist.
In this case it returns a pair where the first is the inserted iterator ( if successful ) and the second is a boolean that can tell you whether it succeeded.

The behavior you describe only happens with the function
std::map::operator[].

Note that since C++17 there is an insert_or_assign function.

Answer 2

If you want to have duplicate keys then use multimaps