Defined in header
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.
where STATICALLY_WIDEN<CharT>("...") is "..." if
CharT is char, and L"..." if
CharT is wchar_t.
 Return value
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|| |
 See also
| stores formatted representation of the arguments in a new string |
| formatting support for |
(class template specialization)