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

 

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Time point time_point (C++11) clock_time_conversion (C++20)   clock_cast (C++20) Duration duration (C++11) Clocks system_clock (C++11) steady_clock (C++11) is_clock (C++20) utc_clock (C++20) tai_clock (C++20) high_resolution_clock (C++11) gps_clock (C++20) file_clock (C++20) local_t (C++20) Time of day is_amis_pm (C++20)(C++20) make12make24 (C++20)(C++20) hh_mm_ss (C++20)

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std::chrono::duration

Member functions
duration::duration duration::operator= duration::count duration::zero duration::min duration::max duration::operator+duration::operator-	duration::operator++duration::operator-- duration::operator+=duration::operator-=duration::operator*=duration::operator/=duration::operator%=
Non-member functions
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(C++20) operator<< (C++20)	duration_cast floor (C++17) ceil (C++17) round (C++17) abs (C++17) operator""h (C++14) operator""min (C++14) operator""s (C++14) operator""ms (C++14) operator""us (C++14) operator""ns (C++14) from_stream (C++20)
Helper classes
common_type treat_as_floating_point      duration_values	formatter<std::chrono::duration> (C++20) hash<std::chrono::duration> (C++26)

 

Defined in header <chrono>
template< class CharT, class Traits, class Rep, class Period > std::basic_ostream<CharT, Traits>& operator<<( std::basic_ostream<CharT, Traits>& os, const std::chrono::duration<Rep, Period>& d );		(since C++20)

See More

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 Period::type::den == 1	[num]s
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 (C++20)	stores formatted representation of the arguments in a new string (function template)
std::formatter<std::chrono::duration> (C++20)	formatting support for duration (class template specialization)
operator<<operator>>	performs stream input and output on strings (function template)
to_string (C++11)	converts an integral or floating-point value to string (function)
to_wstring (C++11)	converts an integral or floating-point value to wstring (function)