Time Functions (`time.h')

This chapter groups functions used either for reporting on time (elapsed, current, or compute time) or to perform calculations based on time.

The header file `time.h' defines three types. clock_t and time_t are both used for representations of time particularly suitable for arithmetic. (In this implementation, quantities of type clock_t have the highest resolution possible on your machine, and quantities of type time_t resolve to seconds.) size_t is also defined if necessary for quantities representing sizes.

`time.h' also defines the structure tm for the traditional representation of Gregorian calendar time as a series of numbers, with the following fields:

tm_sec

Seconds.

tm_min

Minutes.

tm_hour

Hours.

tm_mday

Day.

tm_mon

Month.

tm_year

Year (since 1900).

tm_wday

Day of week: the number of days since Sunday.

tm_yday

Number of days elapsed since last January 1.

tm_isdst

Daylight Savings Time flag: positive means DST in effect, zero means DST not in effect, negative means no information about DST is available.

• asctime: Format time as string
• clock: Cumulative processor time
• ctime: Convert time to local and format as string
• difftime: Subtract two times
• gmtime: Convert time to UTC (GMT) traditional representation
• localtime: Convert time to local representation
• mktime: Convert time to arithmetic representation
• strftime: Flexible calendar time formatter
• time: Get current calendar time (as single number)