time.h File Reference

Time-related functions. More...

Go to the source code of this file.

Classes
struct	tm
	Used to get information about the current time. More...
struct	timeval
	Rappresents time. More...
struct	itimerval
	Rappresents a time interval. More...
struct	timespec
	Specify intervals of time with nanosecond precision. More...

Macros
#define	ITIMER_REAL   0
	This timer counts down in real (i.e., wall clock) time. At each expiration, a SIGALRM signal is generated.
#define	ITIMER_VIRTUAL   1
	This timer counts down against the user-mode CPU time consumed by the process. At each expiration, a SIGVTALRM signal is generated.
#define	ITIMER_PROF   2
	This timer counts down against the total (i.e., both user and system) CPU time consumed by the process. At each expiration, a SIGPROF signal is generated.

Typedefs
typedef unsigned int	time_t
	Used to store time values.
typedef struct tm	tm_t
	Used to get information about the current time.
typedef struct timeval	timeval_t
	Rappresents time.
typedef struct itimerval	itimerval_t
	Rappresents a time interval.
typedef struct timespec	timespec_t
	Specify intervals of time with nanosecond precision.

Functions
time_t	time (time_t *t)
	Returns the current time. More...
time_t	difftime (time_t time1, time_t time2)
	Return the difference between the two time values. More...
tm_t *	localtime (const time_t *timep)
	The current time broken down into a tm_t structure. More...
size_t	strftime (char *s, size_t max, const char *format, const tm_t *tm)
	Formats the time tm according to the format specification format and places the result in the character array s of size max. More...
int	nanosleep (const struct timespec *req, struct timespec *rem)
	Suspends the execution of the calling thread. More...
unsigned int	sleep (unsigned int seconds)
	Causes the calling thread to sleep either until the number of real-time seconds specified in seconds have elapsed or until a signal arrives which is not ignored. More...
int	getitimer (int which, struct itimerval *curr_value)
	Fills the structure pointed to by curr_value with the current setting for the timer specified by which. More...
int	setitimer (int which, const struct itimerval *new_value, struct itimerval *old_value)
	The system provides each process with three interval timers, each decrementing in a distinct time domain. When any timer expires, a signal is sent to the process, and the timer (potentially) restarts. More...

Detailed Description

Time-related functions.

Copyright

(c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Function Documentation

difftime()

time_t difftime	(	time_t	time1,
		time_t	time2
	)

Return the difference between the two time values.

Parameters

time1	The first time value.
time2	The second time value.

Returns

The difference in terms of seconds.

getitimer()

int getitimer	(	int	which,
		struct itimerval *	curr_value
	)

Fills the structure pointed to by curr_value with the current setting for the timer specified by which.

Parameters

which	which timer.
curr_value	where we place the timer value.

Returns

0 on success, -1 on failure and errno is set to indicate the error.

localtime()

tm_t* localtime

(

const time_t *

timep

)

The current time broken down into a tm_t structure.

Parameters

timep

A pointer to a variable holding the current time.

Returns

The time broken down.

nanosleep()

int nanosleep	(	const struct timespec *	req,
		struct timespec *	rem
	)

Suspends the execution of the calling thread.

Parameters

req	The amount of time we want to sleep.
rem	The remaining time we did not sleep.

Returns

If the call is interrupted by a signal handler, nanosleep() returns -1, sets errno to EINTR, and writes the remaining time into the structure pointed to by rem unless rem is NULL.

The execution is suspended until either at least the time specified in *req has elapsed, or the delivery of a signal that triggers the invocation of a handler in the calling thread or that terminates the process.

setitimer()

int setitimer	(	int	which,
		const struct itimerval *	new_value,
		struct itimerval *	old_value
	)

The system provides each process with three interval timers, each decrementing in a distinct time domain. When any timer expires, a signal is sent to the process, and the timer (potentially) restarts.

Parameters

which	which timer.
new_value	the new value for the timer.
old_value	output variable where the function places the previous value.

Returns

0 on success, -1 on failure and errno is set to indicate the error.

sleep()

unsigned int sleep

(

unsigned int

seconds

)

Causes the calling thread to sleep either until the number of real-time seconds specified in seconds have elapsed or until a signal arrives which is not ignored.

Parameters

seconds

The number of seconds we want to sleep.

Returns

Zero if the requested time has elapsed, or the number of seconds left to sleep, if the call was interrupted by a signal handler.

strftime()

size_t strftime	(	char *	s,
		size_t	max,
		const char *	format,
		const tm_t *	tm
	)

Formats the time tm according to the format specification format and places the result in the character array s of size max.

Parameters

s	The destination buffer.
max	The maximum length of the buffer.
format	The buffer used to generate the time.
tm	The broken-down time.

Returns

The number of bytes (excluding the terminating null) placed in s.

time()

time_t time

(

time_t *

t

)

Returns the current time.

Parameters

t	Where the time should be stored.

Returns

The current time.