Queues Pseudocode

1procedure ENQUEUE(Q, x)
2  rear ← rear + 1
3  Q[rear] ← x
4end procedure

1procedure DEQUEUE(Q)
2  if front > rear then
3    error "UNDERFLOW"
4  end if
5  x ← Q[front]
6  front ← front + 1
7  return x
8end procedure

1procedure FRONT(Q)
2  if front > rear then
3    error "EMPTY"
4  end if
5  return Q[front]
6end procedure

1procedure ENQUEUE_CIRC(Q, x)
2  if (rear + 1) mod size = front then error "FULL"
3  if front = −1 then
4    front ← 0
5  end if
6  rear ← (rear + 1) mod size
7  Q[rear] ← x
8end procedure