pointers - C thread argument -

basic function of program: create number of counters (0), create number of instructions per threads, create struct instructions contain counter*, repetitions , work_fn (increment, decrement etc). program build dynamic structure (already coded up) spawn threads , join. 1 thread can have more 1 instructions.

static void* worker_thread(void *arg){   long long *n;   pthread_mutex_lock( &lock1 );    n = (long long *) arg;   printf("testing: %lld.\n", n);    pthread_mutex_unlock( &lock1 );    return null; }  //nthreads total number of threads  for(int i=0; < nthreads ; i++){   pthread_create( &thread_id[i], null, worker_thread, &i); //problem }   for(int i=0; < nthreads ; i++){   pthread_join( thread_id[i], null); } 

i trying test thread function, firstly create number of threads join them. can't seems pass current thread number [i] in case worker thread function.

int n = (int)arg; 

in worker_thread function.

and

(void*)i 

instead of &i in thread spawn