std::chrono::operator<<(std::chrono::month)

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

If !m.ok(), inserts unsigned(m) followed by " is not a valid month" to os. Otherwise, forms a std::basic_string<CharT> s consisting of the abbreviated month name for the month represented by m, determined using the locale associated with os, and inserts s into os

Equivalent to

return os << (m.ok ( ) ?
std::format (os.getloc ( ), STATICALLY_WIDEN<CharT> ( "{:L%b}" ), m) :
std::format (os.getloc ( ), STATICALLY_WIDEN<CharT> ( "{} is not a valid month" ), unsigned (m) ) ) ;

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

Return value

os

Notes

This operator<< is primarily intended for debugging use. For control over formatting, use std::format

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

format (C++20)	stores formatted representation of the arguments in a new string (function template)
std::formatter<std::chrono::month> (C++20)	formatting support for month (class template specialization)