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

From cppreference.com
< cpp‎ | chrono‎ | year
 
 
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template <class CharT, class Traits>

std::basic_ostream<CharT, Traits>&

operator<<(std::basic_ostream<CharT, Traits>& os, const std::chrono::year& y);
(since C++20)

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.

[edit] Return value

os.

[edit] See also

(C++20)
stores formatted representation of the arguments in a new string
(function template) [edit]
specialization of std::formatter that formats a year according to the provided format
(class template specialization) [edit]