# libc - Calendar Time

File: libc.info | Node: Calendar Time | Next: Setting an Alarm | Prev: Processor Time | Up: Date and Time

### Calendar Time

This section describes facilities for keeping track of dates and times according to the Gregorian calendar.

There are three representations for date and time information:

- "Calendar time" (the `time_t' data type) is a compact representation, typically giving the number of seconds elapsed since some implementation-specific base time.

- There is also a "high-resolution time" representation (the `struct timeval' data type) that includes fractions of a second. Use this time representation instead of ordinary calendar time when you need greater precision.

- "Local time" or "broken-down time" (the `struct tm' data type) represents the date and time as a set of components specifying the year, month, and so on, for a specific time zone. This time representation is usually used in conjunction with formatting date and time values.

* Menu:

* Simple Calendar Time:: | Facilities for manipulating calendar time.
* High-Resolution Calendar:: | A time representation with greater precision.
* Broken-down Time:: | Facilities for manipulating local time.
* Formatting Date and Time:: | Converting times to strings.
* TZ Variable:: | How users specify the time zone.
* Time Zone Functions:: | Functions to examine or specify the time zone.
* Time Functions Example:: | An example program showing use of some of the time functions.

Next: Setting an Alarm | Up: Date and Time

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