bitvector& operator=(const bitvector& x);
Assigns x to *this.
Postcondition: *this == x.
If capacity() >= x.size(), no exception can be thrown.
void assign(size_type n, bool x);
Assigns to *this n copies of x.
Postcondition: *this == bitvector(n, x).
If capacity() >= n, no exception can be thrown.
template <class InputIterator>
void assign(InputIterator first, InputIterator last);
Assigns to *this the range [first, last).
Precondition: first and last are not iterators into this bitvector.
Postcondition: *this == bitvector(first, last).
If capacity() >= distance(first, last), and if no operations on the InputIterator type can throw, then no exception can be thrown.