CODEWITHSUNDEEP
clinuxpthreadssemaphore
Eren Berk Saltaş
Eren Berk Saltaş

Reputation: 21

Can I reach C semaphore value ? (sem_t)

To enter into if, I need to reach the value in "t" variable. Is there any way I can do this?

int main(int argc , char* argv[]){

    sem_t t;
    sem_init(&t, 0 /*#ofP*/, 1/*Semaphore start value*/);

    if(t > 0){

        printf("Hello");
    }

    return 0;
}

Upvotes: 1

Views: 1933

Answers (1)

catnip
catnip

Reputation: 25388

You can use sem_getvalue (error checking omitted for brevity):

sem_t t;
sem_init (&t, 0 /*#ofP*/, 1 /*Semaphore start value*/);

int sval;
sem_getvalue (&t, &sval);
if (sval > 0)
    printf ("Hello");

However: semaphores are generally used in a multi tasking / multi threaded context, so the value can change from underneath you at any time. If your goal is to wait on the semaphore until it is signalled, use sem_wait (or sem_trywait or sem_timedwait) instead.

Upvotes: 3

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