C Date and time utilities

Defined in header `<ctime>`
Time manipulation
difftime	computes the difference between times (function)
time	returns the current time of the system as time since epoch (function)
clock	returns raw processor clock time since the program is started (function)
timespec_get (since C++17)	returns the calendar time based on a given time base (function)
Format conversions
asctime	converts a `tm` object to a textual representation (function)
ctime	converts a `time_t` object to a textual representation (function)
strftime	converts a `tm` object to custom textual representation (function)
wcsftime	converts a tm object to custom wide string textual representation (function)
gmtime	converts time since epoch to calendar time expressed as Universal Coordinated Time (function)
localtime	converts time since epoch to calendar time expressed as local time (function)
mktime	converts calendar time to time since epoch (function)

number of processor clock ticks per second
(macro constant)

tm	calendar time type (class)
time_t	time since epoch type (typedef)
clock_t	process running time (typedef)
timespec (since C++17)	time in seconds and nanoseconds (struct)

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
Relational operators
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
`optional`, `any` and `variant` (C++17)
optional
any
variant
in_placein_place_typein_place_indexin_place_tin_place_type_tin_place_index_t
Pairs and tuples
pair
tuple (C++11)
apply (C++17)
make_from_tuple (C++17)
piecewise_construct_t (C++11)
piecewise_construct (C++11)
integer_sequence (C++14)
Swap, forward and move
swap
exchange (C++14)
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
Elementary string conversions
to_chars (C++17)
from_chars (C++17)
chars_format (C++17)
Type operations
declval (C++11)
as_const (C++17)