how to find number of elements in a Circular Queue

Question

how do i find the number of items in a circular queue?

|front - rear| doesnt always work.

is there one equation to know how many element is in a cir

Answer 1

int lenghtQueue(queue* q){

     int len =0 ;
     if (isEmpty(q))
            return 0 ;

      queue* qe = q->next ;
      len ++ ;

       while(qe!=q){
             len ++ ;
             qe=qe->next ;           
       }
           return len ;
  }