Sleep()?

What's the sleep() function for C?

The sleep function, in Windows.h, is used ( most commonly ) for finer time procedures. You could use the stuff in time.h for instance, to put a predetermined pause in your program in seconds. You would have to create a function for this, then simply call it specifying how long you want your program to pause before continuing:

Code:

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/*

    Function:
    wait_a_moment(int seconds)
   
    Purpose:
    Provide a predetermined pause in the program
    giving the user enough time to read a message.
    Continue program execution after time is up
    without any user interaction.
   
    Usage:
    wait_a_moment(3) - Pauses for 3 seconds
    wait_a_moment(5) - Pauses for 5 seconds
   
*/

#include <time.h>

void wait_a_moment(int seconds);

void wait_a_moment(int seconds)
{
    clock_t endtime = clock() + seconds * CLOCKS_PER_SEC;
    while ( ( clock() < endtime ) );
}

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Sleep, is used in miliseconds:

Code:

---

#include <windows.h>
#include <stdio.h>

int main()
{
        printf("Pausing..");
        Sleep(200);
        return 0;
}

---

The sleep function allow you to pause the program for x number of millisecond's, the syntax is:

Code:

---

int main();
{
  sleep(2);
  printf("this is the sleep function.\n");
  return 0;
}

---

The above example is would pause the program for two millisecond's.

Hope that help's.

> int main();
My compiler doesn't like that very much.

How about:

Code:

---

int main()
{
  sleep(2);
  printf("this is the sleep function.\n");
  return 0;
}

---

The only reason i'm confident enough to post help is because i've just learned all about the sleep function. My bad.

Code:

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SLEEP(3)            Linux Programmer's Manual            SLEEP(3)

NAME
      sleep - Sleep for the specified number of seconds

SYNOPSIS
      #include <unistd.h>

      unsigned int sleep(unsigned int seconds);

DESCRIPTION
      sleep() makes the current process sleep until seconds sec-
      onds have  elapsed  or  a  signal  arrives  which  is  not
      ignored.

RETURN VALUE
      Zero  if  the requested time has elapsed, or the number of
      seconds left to sleep.

CONFORMING TO
      POSIX.1

BUGS
      sleep() may be implemented using SIGALRM; mixing calls  to
      alarm() and sleep() is a bad idea.

      Using  longjmp()  from  a  signal handler or modifying the
      handling of SIGALRM while sleeping  will  cause  undefined
      results.

SEE ALSO
      signal(2), alarm(2)

GNU                      April 7, 1993                        1

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Man page for sleep(c)

There, miliseconds, and regular seconds, hope you got enough information.

here's another for ya:

Code:

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NANOSLEEP(2)        Linux Programmer's Manual        NANOSLEEP(2)

NAME
      nanosleep - pause execution for a specified time

SYNOPSIS
      #include <time.h>

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

DESCRIPTION
      nanosleep delays the execution of the program for at least
      the  time specified in *req.  The function can return ear-
      lier if a signal has been delivered  to  the  process.  In
      this  case, it returns -1, sets errno to EINTR, and writes
      the remaining time into the structure pointed  to  by  rem
      unless rem is NULL.  The value of *rem can then be used to
      call nanosleep again and complete the specified pause.

      The structure timespec is used  to  specify  intervals  of
      time  with  nanosecond  precision.  It  is  specified  in
      <time.h> and has the form

              struct timespec
              {
                      time_t  tv_sec;        /* seconds */
                      long    tv_nsec;        /* nanoseconds */
              };

      The value of the nanoseconds field must be in the range  0
      to 999 999 999.

      Compared  to  sleep(3)  and  usleep(3),  nanosleep has the
      advantage of not affecting any signals, it is standardized
      by  POSIX,  it  provides  higher timing resolution, and it
      allows to continue a sleep that has been interrupted by  a
      signal more easily.

ERRORS
      In  case  of  an  error or exception, the nanosleep system
      call returns -1 instead of 0 and sets errno to one of  the
      following values:

      EINTR  The  pause  has  been interrupted by a non-blocked
              signal that was  delivered  to  the  process.  The
              remaining sleep time has been written into *rem so
              that the process can easily call  nanosleep  again
              and continue with the pause.

      EINVAL  The  value  in  the  tv_nsec  field was not in the
              range 0 to 999 999 999 or tv_sec was negative.

BUGS
      The current implementation of nanosleep is  based  on  the
      normal  kernel  timer mechanism, which has a resolution of
      1/HZ s (i.e, 10 ms on Linux/i386 and 1 ms on Linux/Alpha).
      Therefore, nanosleep pauses always for at least the speci-
      fied time, however it can take up to  10  ms  longer  than
      specified  until  the  process becomes runnable again. For
      the same reason, the value returned in case of a delivered
      signal  in *rem is usually rounded to the next larger mul-
      tiple of 1/HZ s.

      As some applications  require  much  more  precise  pauses
      (e.g.,  in  order to control some time-critical hardware),
      nanosleep is also capable of short high-precision  pauses.
      If  the process is scheduled under a real-time policy like
      SCHED_FIFO or SCHED_RR, then pauses of up to 2 ms will  be
      performed as busy waits with microsecond precision.

CONFORMING TO
      POSIX.1b (formerly POSIX.4).

SEE ALSO
      sleep(3), usleep(3), sched_setscheduler(2), and timer_cre-
      ate(2).

Linux 1.3.85                1996-04-10                          1

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little fact about Sleep() not sleep()
Sleep is a windows function that is in miliseconds...
the reason it is a windows only function is because windows, when it boots up does these time thigns:
Grabs time from time chip:
Grab a few seconds for randomness and time measurement

when it has the full second in memory it can seperate this into smaller portions this is why it is a windows ONLY function.
The time Chip only has seconds, not milliseconds.

:D Gee, now the new guys don't even have to search for the man pages.