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Difference between revisions of "cpp/chrono/c/timespec"

From cppreference.com
< cpp‎ | chrono‎ | c
m (link to ja)
m (→‎Notes)
 
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{{cpp/title|timespec}}
 
{{cpp/title|timespec}}
 
{{cpp/chrono/c/navbar}}
 
{{cpp/chrono/c/navbar}}
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{{ddcl|header=ctime|since=c++17|
−
{{ddcl | header=ctime | since=c++17 |
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struct timespec;
 
struct timespec;
 
}}
 
}}
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===Member objects===
 
===Member objects===
 
{{dsc begin}}
 
{{dsc begin}}
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{{dsc | nolink=true | {{dsc small|std::time_t}} tv_sec | 2=whole seconds &ndash; &gt;= 0}}
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{{dsc|nolink=true|{{lc|std::time_t}} {{tt|tv_sec}}|2=whole seconds &ndash; &gt;= 0}}
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{{dsc | nolink=true | {{dsc small|long}} tv_nsec | nanoseconds &ndash; [0, 999999999]}}
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{{dsc|nolink=true|{{c|long}} {{tt|tv_nsec}}|nanoseconds &ndash; {{closed range|0|999999999}}}}
 
{{dsc end}}
 
{{dsc end}}
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The declaration order of {{tt|tv_sec}} and {{tt|tv_nsec}} is unspecified. Implementation may add other data members to {{tt|timespec}}.
 +
 +
===Notes===
 +
The type of {{tt|tv_nsec}} is {{c|long long}} on some platforms, which is currently non-conforming in C++, but is allowed in C since C23.
 +
 +
===Example===
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{{example
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|code=
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#include <ctime>
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#include <iostream>
 +
 +
int main()
 +
{
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    std::timespec ts;
 +
    std::timespec_get(&ts, TIME_UTC);
 +
    char buff[0x80];
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    std::strftime(buff, sizeof buff, "%D %T", std::gmtime(&ts.tv_sec));
 +
 +
//  auto [sec, nsec] = ts; // UB: structured bindings should not be used because the
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                          // declaration order and data member list are unspecified
 +
 +
    std::cout << "Current time: " << buff << " (UTC)\n"
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              << "Raw timespec.tv_sec: " << ts.tv_sec << '\n'
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              << "Raw timespec.tv_nsec: " << ts.tv_nsec << '\n';
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}
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|p=true
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|output=
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Current time: 04/06/23 12:03:31 (UTC)
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Raw timespec.tv_sec: 1680782611
 +
Raw timespec.tv_nsec: 678437213
 +
}}
  
 
===See also===
 
===See also===
 
{{dsc begin}}
 
{{dsc begin}}
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{{dsc inc | cpp/chrono/c/dsc timespec_get}}
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{{dsc inc|cpp/chrono/c/dsc timespec_get}}
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{{dsc inc | cpp/chrono/c/dsc tm}}
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{{dsc inc|cpp/chrono/c/dsc tm}}
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{{dsc see c | c/chrono/timespec }}
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{{dsc see c|c/chrono/timespec}}
 
{{dsc end}}
 
{{dsc end}}
  
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{{langlinks|ja|zh}}
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{{langlinks|es|ja|ru|zh}}

Latest revision as of 06:49, 4 April 2024

 
C++
 
Utilities library
General utilities
Relational operators (deprecated in C++20)
 
Date and time utilities
Time point
(C++11)
(C++20)
Duration
(C++11)
Clocks
(C++11)
(C++11)
(C++20)
(C++20)
(C++20)
(C++20)
Time of day
(C++20)(C++20)
(C++20)(C++20)
(C++20)

Calendar
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)(C++20)
Time zone
(C++20)
(C++20)
(C++20)(C++20)(C++20)(C++20)  
(C++20)
chrono I/O
(C++20)
C-style date and time
 
C-style date and time utilities
Functions
Time manipulation
(C++17)
Format conversions
Constants
Types
timespec
(C++17)
 
Defined in header <ctime>
struct timespec;
 (since C++17)

Structure holding an interval broken down into seconds and nanoseconds.

Contents

[edit] Member objects

std::time_t tv_sec whole seconds – >= 0
long tv_nsec nanoseconds – [​0​, 999999999]

The declaration order of tv_sec and tv_nsec is unspecified. Implementation may add other data members to timespec.

[edit] Notes

The type of tv_nsec is long long on some platforms, which is currently non-conforming in C++, but is allowed in C since C23.

[edit] Example

Run this code
#include <ctime>
#include <iostream>
 
int main()
{
    std::timespec ts;
    std::timespec_get(&ts, TIME_UTC);
    char buff[0x80];
    std::strftime(buff, sizeof buff, "%D %T", std::gmtime(&ts.tv_sec));
 
//  auto [sec, nsec] = ts; // UB: structured bindings should not be used because the
                           // declaration order and data member list are unspecified
 
    std::cout << "Current time: " << buff << " (UTC)\n"
              << "Raw timespec.tv_sec: " << ts.tv_sec << '\n'
              << "Raw timespec.tv_nsec: " << ts.tv_nsec << '\n';
}

Possible output: 

Current time: 04/06/23 12:03:31 (UTC)
Raw timespec.tv_sec: 1680782611
Raw timespec.tv_nsec: 678437213

[edit] See also

(C++17)
 returns the calendar time in seconds and nanoseconds based on a given time base
(function) [edit]
calendar time type
(class) [edit]
C documentation for timespec
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