Defined in header <chrono>
template <class CharT, class Traits>
std::basic_ostream<CharT, Traits>&
operator<<( std::basic_ostream<CharT, Traits>& os,
            const std::chrono::weekday_indexed& wdi );
(since C++20)

Outputs a textual representation of wdi into the stream os, as if by:

if (wdi.index() >=1 && wdi.index() <= 5) {
os << std::format(os.getloc(), STATICALLY_WIDEN<CharT>("{:L}[{}]"),
wdi.weekday(), wdi.index());
} else {
os << std::format(os.getloc(), STATICALLY_WIDEN<CharT>("{:L}[{} is not a valid index]"),
wdi.weekday(), wdi.index());

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

Return value


Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
P2372R3 C++20 the given locale was used by default L is needed to use the given locale

See also

stores formatted representation of the arguments in a new string
(function template)
specialization of std::formatter that formats a weekday according to the provided format
(class template specialization)

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