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std::tm - cppreference.com

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struct tm;

Structure holding a calendar date and time broken down into its components.

Member objects

int tm_sec

 seconds after the minute – [0, 61](until C++11) [0, 60](since C++11)[note 1]
(public member object)

int tm_min

 minutes after the hour – [0, 59]
(public member object)

int tm_hour

 hours since midnight – [0, 23]
(public member object)

int tm_mday

 day of the month – [1, 31]
(public member object)

int tm_mon

 months since January – [0, 11]
(public member object)

int tm_year

 years since 1900
(public member object)

int tm_wday

 days since Sunday – [0, 6]
(public member object)

int tm_yday

 days since January 1 – [0, 365]
(public member object)

int tm_isdst

 Daylight Saving Time flag. The value is positive if DST is in effect, zero if not and negative if no information is available.
(public member object)
  1. ↑ Range allows for a positive leap second. Two leap seconds in the same minute are not allowed (the range [0, 61] was a defect introduced in C89 and corrected in C99).

Notes

BSD, GNU and musl C library support two additional members, which are standardized in POSIX.1-2024.

seconds east of UTC
(public member object)
timezone abbreviation
(public member object)

Example

#include <ctime>
#include <iostream>

int main()
{
    std::tm tm{};
    tm.tm_year = 2022 - 1900;
    tm.tm_mday = 1;
    std::mktime(&tm);

    std::cout << std::asctime(&tm); // note implicit trailing '\n'
}

Possible output:

See also

converts time since epoch to calendar time expressed as local time
(function) [edit]
converts time since epoch to calendar time expressed as Universal Coordinated Time
(function) [edit]