gmtime

gmtime is a function name used in several programming environments to convert a time value to a broken-down representation of Coordinated Universal Time (UTC). In general, it takes a time value such as a timestamp and returns the components of the corresponding calendar date and time expressed in UTC (year, month, day, hour, minute, second).

In C, the prototype is struct tm *gmtime(const time_t *timep). It returns a pointer to a statically allocated struct tm containing fields such as tm_year, tm_mon, tm_mday, tm_hour, tm_min, tm_sec, tm_wday, and tm_yday. The time is in UTC, and tm_isdst is typically 0. The function may return NULL if the time value cannot be represented. Because it uses static storage, successive calls overwrite previous results, and the function is not thread-safe. Portable applications often prefer gmtime_r (POSIX) or gmtime_s (Windows) for thread safety. The reverse operation, converting a UTC broken-down time to a time value, is performed by timegm (GNU) or _mkgmtime on Windows.

In Python, time.gmtime([seconds]) returns a time.struct_time in UTC. If seconds is omitted, the current time is used. The result is a new object, and the call is thread-safe. It is commonly used for formatting or for converting timestamps to calendar fields in UTC.

See also: time.localtime, mktime, time module utilities that handle local time and conversions between time representations.