namespace std {
template<> struct char_traits<char16_t> {
using char_type = char16_t;
using int_type = uint_least16_t;
using off_type = streamoff;
using pos_type = u16streampos;
using state_type = mbstate_t;
using comparison_category = strong_ordering;
static constexpr void assign(char_type& c1, const char_type& c2) noexcept;
static constexpr bool eq(char_type c1, char_type c2) noexcept;
static constexpr bool lt(char_type c1, char_type c2) noexcept;
static constexpr int compare(const char_type* s1, const char_type* s2, size_t n);
static constexpr size_t length(const char_type* s);
static constexpr const char_type* find(const char_type* s, size_t n,
const char_type& a);
static constexpr char_type* move(char_type* s1, const char_type* s2, size_t n);
static constexpr char_type* copy(char_type* s1, const char_type* s2, size_t n);
static constexpr char_type* assign(char_type* s, size_t n, char_type a);
static constexpr int_type not_eof(int_type c) noexcept;
static constexpr char_type to_char_type(int_type c) noexcept;
static constexpr int_type to_int_type(char_type c) noexcept;
static constexpr bool eq_int_type(int_type c1, int_type c2) noexcept;
static constexpr int_type eof() noexcept;
};
}
The two-argument members
assign,
eq, and
lt are defined identically to
the built-in operators
=,
==, and
<, respectively
.The member
eof() returns an
implementation-defined constant that cannot appear
as a valid UTF-16 code unit
.