std::chrono::operator<<(std::chrono::day)
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std::chrono::day
Member functions
Nonmember functions
operator<<
Helper classes
(C++26)
Defined in header
<chrono>
template< class CharT, class Traits >
(since C++20)
std::basic_ostream <CharT, Traits>&
Forms a std::basic_string <CharT> s consisting of the day value stored in d formatted as a decimal number, with a leading zero if the result would otherwise be a single decimal digit. Then, if !d.ok(), append " is not a valid day" to the formatted string. Inserts that string into os.
Equivalent to
return os << (d.ok() ?
std::format (STATICALLY_WIDEN<CharT>("{:%d}"), d) :
std::format (STATICALLY_WIDEN<CharT>("{:%d} is not a valid day"), d));
where STATICALLY_WIDEN<CharT>("...") is "..." if CharT is char, and L"..." if CharT is wchar_t.
[edit] Return value
os
[edit] Example
Run this code
#include <chrono> #include <iostream> int main() { constexpr std::chrono::day d1{31}, d2{7}, d3{42}, d4{}; std::cout << d1 << '\n' << d2 << '\n' << d3 << '\n' << d4 << '\n'; }
Possible output:
31 07 42 is not a valid day 00 is not a valid day