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

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< cpp‎ | chrono‎ | duration
 
 
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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)

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.

[edit] Return value

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

[edit] See also

(C++20)
stores formatted representation of the arguments in a new string
(function template) [edit]
specialization of std::formatter that formats a duration according to the provided format
(class template specialization) [edit]
performs stream input and output on strings
(function template) [edit]
(C++11)
converts an integral or floating point value to string
(function) [edit]
converts an integral or floating point value to wstring
(function) [edit]