std::chrono::operator<<(std::chrono::year)

template <class CharT, class Traits>
std::basic_ostream<CharT, Traits>&
operator<<(std::basic_ostream<CharT, Traits>& os, const std::chrono::year& y);

Forms a std::basic_string<CharT> s consisting of the year value stored in y formatted as a decimal number, left-padded with 0 to four digits if the result would otherwise be less than four digits. Then, if !y.ok(), append " is not a valid year" to the formatted string. Inserts that string into os.

Equivalent to.

return os << (y.ok() ?
std::format(STATICALLY_WIDEN<CharT>("{:%Y}"), y) :
std::format(STATICALLY_WIDEN<CharT>("{:%Y} is not a valid year"), y));

where STATICALLY_WIDEN<CharT>("...") is "..." if CharT is char, and L"..." if CharT is wchar_t.

Return value

os.

See also