explicit ptr_vector( size_type to_reserve );

• constructs an empty vector with a buffer of size least to_reserve

size_type capacity() const;

• Effects: Returns the size of the allocated buffer
• Throws: Nothing

void reserve( size_type n );

• Requirements: n <= max_size()
• Effects: Expands the allocated buffer
• Postcondition: capacity() >= n
• Throws: std::length_error() if n > max_size()

T& operator[]( size_type n );

const T& operator[]( size_type n ) const;

• Requirements: n < size()
• Effects: Returns a reference to the n'th element
• Throws: Nothing

T& at( size_type n );

const T& at( size_type n ) const;

• Requirements: n < size()
• Effects: Returns a reference to the n'th element
• Throws: bad_index if n >= size()

auto_type replace( size_type idx, T* x );

• Requirements: `` x != 0 and idx < size()``
• Effects: returns the object indexed by idx and replaces it with x.
• Throws: bad_index if idx >= size() and bad_pointer if x == 0.
• Exception safety: Strong guarantee

template< class U > auto_type replace( size_type idx, compatible-smart-ptr<U> x );

• Effects: return replace( idx, x.release() );

bool is_null( size_type idx ) const;

• Requirements: idx < size()
• Effects: returns whether the pointer at index idx is null
• Exception safety: Nothrow guarantee

void transfer( iterator before, T** from, size_type size, bool delete_from = true );

• Requirements: from != 0
• Effects: Takes ownership of the dynamic array from
• Exception safety: Strong guarantee if delete_from == true; if delete_from == false, and an exception is thrown, the container fails to take ownership.
• Remarks: Eventually calls delete[] from if delete_from == true.

T** c_array();

• Returns: 0 if the container is empty; otherwise a pointer to the first element of the stored array
• Throws: Nothing