std::chrono::operator<<(std::chrono::duration)(3)

NAME
std::chrono::operator<<(std::chrono::duration) - std::chrono::operator<<(std::chrono::duration)

Synopsis
   Defined in header <chrono>
   template<
       class CharT,
       class Traits,
       class Rep, (since C++20)
       class Period
   > std::basic_ostream<CharT, Traits>&
       operator<<( std::basic_ostream<CharT, Traits>& os,
                   const std::chrono::duration<Rep, Period>& d );
   Inserts a textual representation of d into os.
   Behaves as if it was implemented as
 std::basic_ostringstream<CharT, Traits> s;
 s.flags(os.flags());
 s.imbue(os.getloc());
 s.precision(os.precision());
 s << d.count() << units_suffix; // see below
 return os << s.str();
   In other words, the stream flags, locale, and precision are determined by the
   stream, but any padding are determined using the entire output string.
   The units_suffix is determined based on Period::type according to the following
   table.
   Period::type Suffix
   std::atto as
   std::femto fs
   std::pico ps
   std::nano ns
   std::micro µs (U+00B5) or us, it is implementation-defined which one is
                        used
   std::milli ms
   std::centi cs
   std::deci ds
   std::ratio<1> s
   std::deca das
   std::hecto hs
   std::kilo ks
   std::mega Ms
   std::giga Gs
   std::tera Ts
   std::peta Ps
   std::exa Es
   std::ratio<60> min
   std::ratio<3600> h
   std::ratio<86400> d
   None of the above, and [num]s
   Period::type::den == 1
   None of the above [num/den]s
   For the last two rows of the table, num and den in the suffix are Period::type::num
   and Period::type::den formatted as a decimal number with no leading zeroes,
   respectively.

Return value
   A reference to the stream, i.e., os.

Example
   This example shows the output of std::chrono::operator<< when given a duration: // Run this code
 #include <chrono>
 #include <iostream>
 using namespace std::chrono_literals;
 int main()
 {
     constexpr auto duration = 123ms;
     std::cout << duration << '\n';
 }

Output:
 123ms

See also
   format stores formatted representation of the
   (C++20) arguments in a new string
                        (function template)
   std::formatter<std::chrono::duration> formatting support for duration
   (C++20) (class template specialization)
   operator<< performs stream input and output on strings
   operator>> (function template)
   to_string converts an integral or floating-point value
   (C++11) to string
                        (function)
   to_wstring converts an integral or floating-point value
   (C++11) to wstring
                        (function)