Minor lab4 changes

Lab4/Lab4.c

@@ -6,6 +6,8 @@
  * Question 6: You see the number 1 almost never. The number of loops at this point almost guarantees that the threads will be reading/writing at the same time, and the counter missing increments/decrements.
  *
  * Question 8: The number 1 is the only thing displayed. This is because the mutex lock ensures that the threads will not be reading/writing at the same time, and the counter will not miss increments/decrements. When another thread tried to lock the mutex, it waits for it to first become unlocked, ensuring proper thread synchronization.
+ *
+ * Question 13: 
  */
 
 
@@ -29,6 +31,7 @@ void *inc() {
 		gv++;
 		pthread_mutex_unlock(&mutex);
 	}
+	return NULL;
 }
 
 void *dec() {
@@ -37,6 +40,7 @@ void *dec() {
 		gv--;
 		pthread_mutex_unlock(&mutex);
 	}
+	return NULL;
 }
 
 void *minus() {
@@ -55,7 +59,7 @@ void *plus(void *argg) {
 
 	for (i = 0; i < 10; i++) {
 		printf("+");
-		//usleep(interval);
+		usleep(interval);
 		sem_post(&sem);
 	}
 	return NULL;
@@ -85,8 +89,8 @@ int main(int argc, char **argv) {
 		unsigned int *t = (unsigned int *) malloc(sizeof(unsigned int));
 		*t = rand();
 
-		pthread_create(&(thread[i]), NULL, &plus, (void *) t);
-		pthread_create(&(thread[i + 1]), NULL, &minus, NULL);
+		pthread_create(&thread[i], NULL, &plus, (void *) t);
+		pthread_create(&thread[i + 1], NULL, &minus, NULL);
 
 		pthread_join(thread[i], NULL);
 		pthread_join(thread[i + 1], NULL);