Date and time utilities

Functions

Time manipulation
Defined in header <time.h>
difftime	computes the difference between times (function)
time	returns the current calendar time of the system as time since epoch (function)
clock	returns raw processor clock time since the program is started (function)
timespec_get (C11)	returns the calendar time in seconds and nanoseconds based on a given time base (function)
timespec_getres (C23)	returns the resolution of calendar time based on a given time base (function)
Format conversions
Defined in header <time.h>
asctimeasctime_s (deprecated in C23)(C11)	converts a tm object to a textual representation (function)
ctimectime_s (deprecated in C23)(C11)	converts a time_t object to a textual representation (function)
strftime	converts a tm object to custom textual representation (function)
Defined in header <wchar.h>
wcsftime (C95)	converts a tm object to custom wide string textual representation (function)
Defined in header <time.h>
gmtimegmtime_rgmtime_s (C23)(C11)	converts time since epoch to calendar time expressed as Coordinated Universal Time (UTC) (function)
localtimelocaltime_rlocaltime_s (C23)(C11)	converts time since epoch to calendar time expressed as local time (function)
mktime	converts calendar time to time since epoch (function)

Constants

Defined in header <time.h>
CLOCKS_PER_SEC	number of processor clock ticks per second (macro constant)

Types

Defined in header <time.h>
tm	calendar time type (struct)
time_t	calendar time since epoch type (typedef)
clock_t	processor time since era type (typedef)
timespec (C11)	time in seconds and nanoseconds (struct)

References

• C17 standard (ISO/IEC 9899:2018):
• 7.27 Date and time <time.h> (p: 284-291)
• 7.29.5.1 The wcsftime function (p: 320-321)
• 7.31.14 Date and time <time.h> (p: 333)
• C11 standard (ISO/IEC 9899:2011):
• 7.27 Date and time <time.h> (p: 388-397)
• 7.29.5.1 The wcsftime function (p: 439-440)
• 7.31.14 Date and time <time.h> (p: 456)
• C99 standard (ISO/IEC 9899:1999):
• 7.23 Date and time <time.h> (p: 338-347)
• 7.24.5.1 The wcsftime function (p: 385-386)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.12 DATE AND TIME <time.h>

See also

C++ documentation for C Date and time utilities