NAME¶

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

Synopsis¶

Defined in header <chrono>
template< class CharT, class Traits >

std::basic_ostream<CharT, Traits>& (since C++20)

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

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.

Return value¶

os

Example¶

// Run this code

#include <chrono>
#include <iostream>

int main()
{
constexpr std::chrono::year y1{2020}, y2{-020}, y3{98304};
std::cout << y1 << '\n'
<< y2 << '\n'
<< y3 << '\n';
}

Possible output:¶

2020
-0016
-32768 is not a valid year

See also¶

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