C, error of compilation during using "usleep" function

Question

I use Ubuntu Linux. When I try use "usleep" function, I get information about "implicit declaration of function usleep". Below is the error code:

muteks.c:70:4: warning: implicit declaration of function ‘usleep’ [-Wimplicit-function-declaration]
    usleep(300);
    ^

Source code:

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <pthread.h>

void * klientWatek (void* arg);
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static int lKf = 10;
int lKl = 15;

int main ()
{
        pthread_t *klientTab;
        int *klientTabId;
        int lKr = 1;
        int i;
        // pamięć dla identyfikatora wątku
        klientTab = (pthread_t *) malloc (lKl* sizeof (pthread_t));
        klientTabId = (int *) malloc (lKl*sizeof (int)); //pamięć dla id
        // będącego argumentem przekazywanym do  funkcji
        for (i=0; i<lKl; i++) klientTabId[i]=i; //przypisanie

        printf("\nOtwieramy pub (simple)!\n");
        printf("\nLiczba wolnych kufli %d\n", lKf);

        for (i=0; i<lKl; i++)
        {
                pthread_create (&klientTab[i], NULL, klientWatek, 
                &klientTabId[i]);
        }

        for (i=0; i<lKl; i++)
        { //wątek joinable, ręcznie zwalniamy zasoby
                pthread_join (klientTab[i], NULL);
        }

        printf("\nZamykamy pub!\n");
        printf("\nLiczba wolnych kufli %d\n", lKf);

void * klientWatek (void * argWsk)//zostanie przekazany klientTabId[i]
{
        int mojId = * ( (int *) argWsk);
        int i,j;

        int pobranoKufel = 0;
        int ileMuszeWypic = 2;

        printf ("\nKlient %d, wchodzę do pubu\n", mojId);

        for (i=0; i<ileMuszeWypic; i++)
        {
           do
           {
              pthread_mutex_lock(&mutex);
              if (lKf > 0)
              {
                printf("\nSprawdziłem, czy jest wolny kufel\n");
                lKf--;
                pobranoKufel = 1;
                printf("\nWziąłem kufel\n");
              }

              pthread_mutex_unlock(&mutex);
            } while (pobranoKufel == 0);
          printf("\nKlient %d, wybieram kufel\n", mojId);

          j=0;
          printf("\nKlient %d, nalewam z kranu %d\n", mojId, j);
          usleep(300);

          printf("\nKlient %d, pije\n", mojId);
          nanosleep((struct timespec[]){{0, 500000000L}},NULL);

          printf("\nKlient %d, odkladam kufel\n", mojId);

          if (pobranoKufel == 1)
          {
             pthread_mutex_lock(&mutex);
             pobranoKufel=0;
             lKf++;
             pthread_mutex_unlock(&mutex);
          }
        }
        printf("\nKlient %d, wychodzę z pubu\n", mojId);

        return (NULL);
}

The way I tried to compile program:

gcc -Wall -pedantic -std=gnu99 -pthread muteks.c -o przyklad

What shall I do now, to compile that?

P.P · Accepted Answer · 2016-11-06T15:45:38.983

6

usleep() is declared in the standard header unistd.h which you haven't included. Include it:

#include <unistd.h>

On a relevant note: usleep() has been removed since POSIX-2008 and recommends to use nanosleep() instead.

edited Nov 06 '16 at 15:45

answered Nov 06 '16 at 15:39

P.P

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Exactly. Now Everything is ok. Thank you. – Plusce Nov 06 '16 at 15:41
1

@Martini But note that `usleep` has been obsolete since POSIX-2001 and been removed from the standard since POSIX-2008. So, you should consider using `nanosleep()` instead. – P.P Nov 06 '16 at 15:46
Thank you. Shall I use it in this way: `nanosleep((struct timespec[]){{0, 300L}},NULL);` ? – Plusce Nov 06 '16 at 15:49
1

@Martini Yes, that looks good. You'd also want to check the return code of `nanosleep()` if it's failed or been interrupted. – P.P Nov 06 '16 at 15:50
Ok:). Thank you for response! – Plusce Nov 06 '16 at 15:51

score 2 · Answer 2 · answered Nov 06 '16 at 15:40

2

#include <unistd.h>

See the man usleep

answered Nov 06 '16 at 15:40

Glick

111
7

C, error of compilation during using "usleep" function

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