std::localtime
From cppreference.com
C++
Date and time library
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C-style date and time utilities
| Functions | ||||
| Time manipulation | ||||
(C++17) | ||||
| Format conversions | ||||
localtime | ||||
| Constants | ||||
| Types | ||||
(C++17) |
| Defined in header <ctime>
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| std::tm* localtime( const std::time_t* time ); |
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Converts given time since epoch as std::time_t value into calendar time, expressed in local time.
Contents |
[edit] Parameters
| time | - | pointer to a std::time_t object to convert |
[edit] Return value
Pointer to a static internal std::tm object on success, or null pointer otherwise. The structure may be shared between std::gmtime, std::localtime, and std::ctime, and may be overwritten on each invocation.
[edit] Notes
This function may not be thread-safe. The Microsoft CRT implementation is thread-safe.
POSIX requires that this function sets errno to EOVERFLOW if it fails because the argument is too large.
tzset, which reads the environment variable TZ.
[edit] Example
Run this code
#include <ctime> #include <iomanip> #include <iostream> #include <sstream> int main() { setenv("TZ", "/usr/share/zoneinfo/America/Los_Angeles", 1); / POSIX-specific std::tm tm{}; / Zero initialize tm.tm_year = 2020 - 1900; / 2020 tm.tm_mon = 2 - 1; / February tm.tm_mday = 15; / 15th tm.tm_hour = 10; tm.tm_min = 15; tm.tm_isdst = 0; / Not daylight saving std::time_t t = std::mktime(&tm); std::cout << "UTC: " << std::put_time(std::gmtime(&t), "%c %Z") << '\n'; std::cout << "local: " << std::put_time(std::localtime(&t), "%c %Z") << '\n'; }
Possible output:
UTC: Sat Feb 15 18:15:00 2020 GMT local: Sat Feb 15 10:15:00 2020 PST
[edit] See also
| converts time since epoch to calendar time expressed as Universal Coordinated Time (function) [edit] | |
| (C23)(C11) |
converts time since epoch to calendar time expressed as local time (function) [edit] |
| C documentation for localtime
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