std::localtime

C++

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Date and time utilities

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C-style date and time

C-style date and time utilities

Functions

Time manipulation

difftime

time

clock

timespec_get (C++17)

Format conversions

asctime

ctime

strftime

wcsftime

gmtime

localtime

mktime

Constants

CLOCKS_PER_SEC

Types

tm

time_t

clock_t

timespec (C++17)

Defined in header <ctime>
std::tm* localtime( const std::time_t *time );

Converts given time since epoch as std::time_t value into calendar time, expressed in local time.

Parameters

time

-

pointer to a time_t object to convert

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.

Notes

This function may not be thread-safe.

POSIX requires that this function sets errno to EOVERFLOW if it fails because the argument is too large.

POSIX specifies that the timezone information is determined by this function as if by calling tzset, which reads the environment variable TZ.

Example

Run this code

#include <iostream>
#include <iomanip>
#include <ctime>
#include <stdlib.h> // defines putenv in POSIX

int main()
{
    std::time_t t = std::time(nullptr);
    std::cout << "UTC:       " << std::put_time(std::gmtime(&t), "%c%Z") << '\n';
    std::cout << "local:     " << std::put_time(std::localtime(&t), "%c%Z") << '\n';
    // POSIX-specific:
    std::string tz = "TZ=Asia/Singapore";
    putenv(tz.data());
    std::cout << "Singapore: " << std::put_time(std::localtime(&t), "%c%Z") << '\n';
}

Output:

UTC:       Fri Sep 15 14:16:29 2017 GMT
local:     Fri Sep 15 14:16:29 2017 UTC
Singapore: Fri Sep 15 22:16:29 2017 SGT

See also

gmtime

converts time since epoch to calendar time expressed as Universal Coordinated Time (function)