NAME

std::localtime - std::localtime

Synopsis

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 std::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 <sstream>
#include <iomanip>
#include <ctime>

int main()
{
setenv("TZ", "/usr/share/zoneinfo/America/Los_Angeles", 1); // POSIX-specific

std::tm tm{}; // zero initialise
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