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

Assuming you implement it using an array with size N so there are pointers pointing to the front and rear. Use the following formula:

size = front > rear ? (front - rear) : (front+N -  rear);