An initial value assumption about map in c++

Question

I am initializing a map map ex; in C++. I could not find contains_key or similar function in stl, hence I am just using ex[inputString]+

Answer 1

Yes, values that do not exist when accessed with operator[] are default-constructed. For numeric values, this is 0.

That said, you're looking for the count method:

bool hasElement = ex.count("element");