Adds the given number of microseconds to time_. microseconds can also be negative to decrease the value of time_.
Converts a string containing an ISO 8601 encoded date and time to a GTimeVal and puts it into time_. iso_date must include year, month, day, hours, minutes, and seconds. It can optionally include fractions of a second and a time zone indicator. (In the absence of any time zone indication, the timestamp is assumed to be in local time.) Since 2.12
Equivalent to the UNIX gettimeofday() function, but portable. You may find g_get_real_time() to be more convenient.
Queries the system monotonic time, if available. On POSIX systems with clock_gettime() and CLOCK_MONOTONIC this call is a very shallow wrapper for that. Otherwise, we make a best effort that probably involves returning the wall clock time (with at least microsecond accuracy, subject to the limitations of the OS kernel). It's important to note that POSIX CLOCK_MONOTONIC does not count time spent while the machine is suspended. On Windows, "limitations of the OS kernel" is a rather substantial statement. Depending on the configuration of the system, the wall clock time is updated as infrequently as 64 times a second (which is approximately every 16ms). Also, on XP (but not on Vista or later) the monotonic clock is locally monotonic, but may differ in exact value between processes due to timer wrap handling. Since 2.28
Queries the system wall-clock time. This call is functionally equivalent to g_get_current_time() except that the return value is often more convenient than dealing with a GTimeVal. You should only use this call if you are actually interested in the real wall-clock time. g_get_monotonic_time() is probably more useful for measuring intervals. Since 2.28
Converts time_ into an RFC 3339 encoded string, relative to the Coordinated Universal Time (UTC). This is one of the many formats allowed by ISO 8601. ISO 8601 allows a large number of date/time formats, with or without punctuation and optional elements. The format returned by this function is a complete date and time, with optional punctuation included, the UTC time zone represented as "Z", and the tv_usec part included if and only if it is nonzero, i.e. either "YYYY-MM-DDTHH:MM:SSZ" or "YYYY-MM-DDTHH:MM:SS.fffffZ". This corresponds to the Internet date/time format defined by RFC 3339, and to either of the two most-precise formats defined by the W3C Note "Date and Time Formats". Both of these documents are profiles of ISO 8601. Use g_date_time_format() or g_strdup_printf() if a different variation of ISO 8601 format is required. Since 2.12
Pauses the current thread for the given number of microseconds. There are 1 million microseconds per second (represented by the G_USEC_PER_SEC macro). g_usleep() may have limited precision, depending on hardware and operating system; don't rely on the exact length of the sleep.
The GDate data structure represents a day between January 1, Year 1, and sometime a few thousand years in the future (right now it will go to the year 65535 or so, but g_date_set_parse() only parses up to the year 8000 or so - just count on "a few thousand"). GDate is meant to represent everyday dates, not astronomical dates or historical dates or ISO timestamps or the like. It extrapolates the current Gregorian calendar forward and backward in time; there is no attempt to change the calendar to match time periods or locations. GDate does not store time information; it represents a day.
The GDate implementation has several nice features; it is only a 64-bit struct, so storing large numbers of dates is very efficient. It can keep both a Julian and day-month-year representation of the date, since some calculations are much easier with one representation or the other. A Julian representation is simply a count of days since some fixed day in the past; for GDate the fixed day is January 1, 1 AD. ("Julian" dates in the GDate API aren't really Julian dates in the technical sense; technically, Julian dates count from the start of the Julian period, Jan 1, 4713 BC).
GDate is simple to use. First you need a "blank" date; you can get a dynamically allocated date from g_date_new(), or you can declare an automatic variable or array and initialize it to a sane state by calling g_date_clear(). A cleared date is sane; it's safe to call g_date_set_dmy() and the other mutator functions to initialize the value of a cleared date. However, a cleared date is initially invalid, meaning that it doesn't represent a day that exists. It is undefined to call any of the date calculation routines on an invalid date. If you obtain a date from a user or other unpredictable source, you should check its validity with the g_date_valid() predicate. g_date_valid() is also used to check for errors with g_date_set_parse() and other functions that can fail. Dates can be invalidated by calling g_date_clear() again.
It is very important to use the API to access the GDate struct. Often only the day-month-year or only the Julian representation is valid. Sometimes neither is valid. Use the API.
GLib also features GDateTime which represents a precise time.