# std::chrono::operator<< (std::chrono::year_month_day)

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< cpp‎ | chrono‎ | year month day

template< class CharT, class Traits > std::basic_ostream <CharT, Traits>& operator<<( std::basic_ostream <CharT, Traits>& os, const std::chrono::year_month_day & ymd); |  | (since C++20)

Outputs a textual representation of `ymd` into the stream `os`. This first forms a std::basic_string <CharT> s consisting of a textual representation of the date in the format `yyyy-mm-dd` (same as the one output by `to_stream` with the %F specifier), and inserts it into `os`. Then, if !ymd.ok(), inserts " is not a valid date" into `os`.

### Return value

`os`.

### Notes

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

### See also

to_stream | outputs a `year_month_day` into a stream according to the provided format (function template)

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