25 Time library [time]

25.5 Class template duration [time.duration]

25.5.10 I/O [time.duration.io]

template<class charT, class traits, class Rep, class Period>
  basic_ostream<charT, traits>&
    operator<<(basic_ostream<charT, traits>& os, const duration<Rep, Period>& d);

Requires: Rep is an integral type whose integer conversion rank ([conv.rank]) is greater than or equal to that of short, or a floating point type.

charT is char or wchar_t.

Effects: Forms a basic_string<charT, traits> from d.count() using to_string if charT is char, or to_wstring if charT is wchar_t.

Appends the units suffix described below to the basic_string.

Inserts the resulting basic_string into os.

[ Note

This specification ensures that the result of this streaming operation will obey the width and alignment properties of the stream.

— end note

]

The units suffix depends on the type Period::type as follows:

(3.1)
If Period::type is atto, the suffix is "as".
(3.2)
Otherwise, if Period::type is femto, the suffix is "fs".
(3.3)
Otherwise, if Period::type is pico, the suffix is "ps".
(3.4)
Otherwise, if Period::type is nano, the suffix is "ns".
(3.5)
Otherwise, if Period::type is micro, the suffix is "μs" ("\u00b5\u0073").
(3.6)
Otherwise, if Period::type is milli, the suffix is "ms".
(3.7)
Otherwise, if Period::type is centi, the suffix is "cs".
(3.8)
Otherwise, if Period::type is deci, the suffix is "ds".
(3.9)
Otherwise, if Period::type is ratio<1>, the suffix is "s".
(3.10)
Otherwise, if Period::type is deca, the suffix is "das".
(3.11)
Otherwise, if Period::type is hecto, the suffix is "hs".
(3.12)
Otherwise, if Period::type is kilo, the suffix is "ks".
(3.13)
Otherwise, if Period::type is mega, the suffix is "Ms".
(3.14)
Otherwise, if Period::type is giga, the suffix is "Gs".
(3.15)
Otherwise, if Period::type is tera, the suffix is "Ts".
(3.16)
Otherwise, if Period::type is peta, the suffix is "Ps".
(3.17)
Otherwise, if Period::type is exa, the suffix is "Es".
(3.18)
Otherwise, if Period::type is ratio<60>, the suffix is "min".
(3.19)
Otherwise, if Period::type is ratio<3600>, the suffix is "h".
(3.20)
Otherwise, if Period::type::den == 1, the suffix is "[num]s".
(3.21)
Otherwise, the suffix is "[num/den]s".

In the list above the use of num and den refer to the static data members of Period::type, which are converted to arrays of charT using a decimal conversion with no leading zeroes.

If Period::type is micro, but the character U+00B5 cannot be represented in the encoding used for charT, the unit suffix "us" is used instead of "μs".

Returns: os.

🔗

template<class charT, class traits, class Rep, class Period>
  basic_ostream<charT, traits>&
    to_stream(basic_ostream<charT, traits>& os, const charT* fmt,
              const duration<Rep, Period>& d);

Effects: Streams d into os using the format specified by the NTCTS fmt.

fmt encoding follows the rules specified in [time.format].

Returns: os.

🔗

template<class charT, class traits, class Rep, class Period, class Alloc = allocator<charT>>
  basic_istream<charT, traits>&
    from_stream(basic_istream<charT, traits>& is, const charT* fmt,
                duration<Rep, Period>& d,
                basic_string<charT, traits, Alloc>* abbrev = nullptr,
                minutes* offset = nullptr);

Effects: Attempts to parse the input stream is into the duration d using the format flags given in the NTCTS fmt as specified in [time.parse].

If the parse parses everything specified by the parsing format flags without error, and yet none of the flags impacts a duration, d will be assigned a zero value.

If %Z is used and successfully parsed, that value will be assigned to *abbrev if abbrev is non-null.

If %z (or a modified variant) is used and successfully parsed, that value will be assigned to *offset if offset is non-null.

Returns: is.