[string.view.access]

constexpr const_reference operator[](size_type pos) const;

Throws: Nothing.

constexpr const_reference at(size_type pos) const;

Throws: out_of_range if pos >= size().

constexpr const_reference front() const;

Throws: Nothing.

constexpr const_reference back() const;

Throws: Nothing.

constexpr const charT* data() const noexcept;

[Note 2:

Unlike basic_string::data() and string-literals, data() can 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]

27 Strings library [strings]