Why is there no [] operator for std::multimap?

Question

Why is there no [] operator for std::multimap?

In errors with multimap (key type is std::string), people say "it makes no sense to extract elements out of it -- there are multiple values per each index". To me, it makes perfect sense and this is why there is equal_range.

So, why did they decided not to add a [] operator for multimap then?

I feel it is because things like myMultiMap[key] = value would be complex to handle but I am really not sure about that.

Answer 1

This might be because of ambiguity as multiMap[key] can represent many elements depending upon the number of insertion with same key.

The operator[] always returns an lvalue reference to the element present at provided index of any randomly accessible container(s), so in case of multimap(s) there will be more than one element for the same key.

Note this is not same as the collision in a HashTable based container (std::unordered_map, std::unordered_set) where different keys can have same hash value computed from a hash function causing elements to land in same bucket.