std::tm

From Cppreference

C++ Standard Library
Language Utilities library Strings library Containers library Algorithms library Iterators library Numerics library Input/output library Localizations library Regular expressions library (C++11) Atomic operations library (C++11) Thread support library (C++11)
Utilities library
Date and time utilities
time_point (C++11) duration (C++11) system_clock (C++11) steady_clock (C++11) high_resolution_clock (C++11) C library facilities
C-style date and time utilities
Functions Time manipulation difftime time clock Format conversions asctime ctime strftime gmtime localtime mktime Constants CLOCKS_PER_SEC Types tm time_t

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

Properties
int tm_sec	seconds after the minute – [0, 60][note 1]
int tm_min	minutes after the hour – [0, 59]
int tm_hour	hours since midnight – [0, 23]
int tm_mday	day of the month – [1, 31]
int tm_mon	months since January – [0, 11]
int tm_year	years since 1900
int tm_wday	days since Sunday – [0, 6]
int tm_yday	days since January 1 – [0, 365]
int tm_isdst	Daylight Saving Time flag. The value ist positive if DST is in effect, zero if not and negative if no information is available

[edit] Notes

1. ↑ Range allows for a positive leap second.

[edit] See also

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