Queue using Arrays

Write a C program to implement a queue data structure using arrays. The queue should support the following operations:

• enqueue(int x): Add an item to the rear of the queue
• dequeue(): Remove an item from the front of the queue and return it
• front(): Get the front item from the queue without removing it
• isEmpty(): Check if the queue is empty
• isFull(): Check if the queue is full

Example 1

  
Input:
enqueue(10)
enqueue(20)
enqueue(30)
front()
dequeue()
front()
dequeue()
dequeue()
isEmpty()
  
Output: 10, 10, 20, 30, true
  
Explanation:
Step 1: enqueue(10) - Queue becomes [10]

Step 2: enqueue(20) - Queue becomes [10, 20]

Step 3: enqueue(30) - Queue becomes [10, 20, 30]

Step 4: front() returns 10 (the front element)

Step 5: dequeue() returns and removes 10 - Queue becomes [20, 30]

Step 6: front() returns 20 (the new front element)

Step 7: dequeue() returns and removes 20 - Queue becomes [30]

Step 8: dequeue() returns and removes 30 - Queue becomes []

Step 9: isEmpty() returns true as the queue is now empty

Example 2

  
Input:
isEmpty()
enqueue(5)
isEmpty()
isFull()
enqueue(10)
enqueue(15)
enqueue(20)
enqueue(25)
isFull()
dequeue()
dequeue()
front()
  
Output: true, false, false, true, 5, 10, 15
  
Explanation:

Step 1: isEmpty() returns true as queue is initially empty

Step 2: enqueue(5) - Queue becomes [5]

Step 3: isEmpty() returns false as queue now has an element

Step 4: isFull() returns false as queue is not full yet

Step 5: enqueue(10) - Queue becomes [5, 10]

Step 6: enqueue(15) - Queue becomes [5, 10, 15]

Step 7: enqueue(20) - Queue becomes [5, 10, 15, 20]

Step 8: enqueue(25) - Queue becomes [5, 10, 15, 20, 25]

Step 9: isFull() returns true as queue has reached its capacity

Step 10: dequeue() returns and removes 5 - Queue becomes [10, 15, 20, 25]

Step 11: dequeue() returns and removes 10 - Queue becomes [15, 20, 25]

Step 12: front() returns 15 (the current front element)

Constraints

  
The maximum size of the queue is fixed (e.g., 100)
  
All operations should have a time complexity of O(1)
  
The queue should handle overflow (when trying to enqueue to a full queue) and underflow (when trying to dequeue from an empty queue)
  
You must implement a circular queue to efficiently use the array space