Modern C++ Programming Cookbook

How it works...

std::vector<bool> is not a standard vector because it is designed to provide space optimization by storing a single bit for each element instead of a Boolean value. Therefore, its elements are not stored in a contiguous sequence and cannot be substituted for an array of Booleans. Due to this:

• The index operator cannot return a reference to a specific element because elements are not stored individually:

        std::vector<bool> bv;        bv.resize(10);        auto& bit = bv[0];      // error

• Dereferencing an iterator cannot produce a reference to bool for the same reason as mentioned earlier:

        auto& bit = *bv.begin(); // error

• There is no guarantee that individual bits can be manipulated independently at the same time from different threads. ...