thread e semafori

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

pthread_mutex_t muta=PTHREAD_MUTEX_INITIALIZER;

int value=0;
int counter;
char* dati[10] = {"pippo", "tizia", "marina", "ursus", "rocco", "adamo", "eva", "fedro", "esopo",
"francesco"};

void* elimina(void* arg) {
    int i,j,tr;
    char* nome;
    nome=malloc(20);


    pthread_mutex_lock(&muta);

    strcpy(nome, dati[counter]); // qui copia il dato

    dati[counter] = NULL;

    tr = pthread_self(); //con la funzione pthread_self si ottiene l’ID del thread chiamante
    usleep((int) (2000000.0*rand()/(RAND_MAX+1.0)));
    printf("Eliminato %s dal thread %d\n",nome,tr);

    counter--; // qui aggiorna il counter della lista dati

pthread_mutex_unlock(&muta);
}

int main () {
    int i;
    counter=9;
    srand((int)time);
    pthread_t thread[10];
    for(i=0;i<10;i++){
        pthread_create (&thread[i], NULL, &elimina, NULL);
    }
    for(i=0;i<10;i++)
        pthread_join(thread[i], NULL);
    return 0;
}