21 Strings library [strings]

21.4 String view classes [string.view]

21.4.3 Class template basic_­string_­view [string.view.template]

21.4.3.5 Element access [string.view.access]

constexpr const_reference operator[](size_type pos) const;
Preconditions: pos < size().
Returns: data_­[pos].
Throws: Nothing.
[Note 1:
Unlike basic_­string​::​operator[], basic_­string_­view​::​operator[](size()) has undefined behavior instead of returning charT().
— end note]
constexpr const_reference at(size_type pos) const;
Returns: data_­[pos].
Throws: out_­of_­range if pos >= size().
constexpr const_reference front() const;
Preconditions: !empty().
Returns: data_­[0].
Throws: Nothing.
constexpr const_reference back() const;
Preconditions: !empty().
Returns: data_­[size() - 1].
Throws: Nothing.
constexpr const_pointer data() const noexcept;
Returns: data_­.
[Note 2:
Unlike basic_­string​::​data() and string-literals, data() may return a pointer to a buffer that is not null-terminated.
Therefore it is typically a mistake to pass data() to a function that takes just a const charT* and expects a null-terminated string.
— end note]