## Is queue FIFO or LIFO?

Stack is a LIFO (last in first out) data structure. The associated link to wikipedia contains detailed description and examples. Queue is a FIFO (first in first out) data structure.

### What does front and rear signifies in queue?

A queue is an ordered collection of items where the addition of new items happens at one end, called the “rear,” and the removal of existing items occurs at the other end, commonly called the “front.” As an element enters the queue it starts at the rear and makes its way toward the front, waiting until that time when …

#### What is head in a stack?

In Scala Stack class , the head() method is utilized to return the top element of the stack.

Why it is known as LIFO?

LIFO is short for “Last In First Out”. The last element pushed onto the stack will be the first element that gets popped off. If you were to pop all of the elements from the stack one at a time then they would appear in reverse order to the order that they were pushed on.

What are the disadvantages of linear queue?

In a linear queue, the traversal through the queue is possible only once,i.e.,once an element is deleted, we cannot insert another element in its position. This disadvantage of a linear queue is overcome by a circular queue, thus saving memory.

## What are the five basic operations on a queue?

Basic Operations of Queue

• Enqueue: Add an element to the end of the queue.
• Dequeue: Remove an element from the front of the queue.
• IsEmpty: Check if the queue is empty.
• IsFull: Check if the queue is full.
• Peek: Get the value of the front of the queue without removing it.

### What is the top of a queue?

priority_queue::top() in C++ STL Priority queues are a type of container adaptors, specifically designed such that the first element of the queue is the greatest of all elements in the queue. priority_queue::top() top() function is used to reference the top(or the largest) element of the priority queue.

#### What is a tail queue?

Creation A tail queue is headed by a structure defined by the TAILQ_HEAD() macro. This structure contains a pair of pointers, one to the first element in the queue and the other to the last element in the queue. The elements are doubly linked so that an arbitrary element can be removed without traversing the queue.

What is LIFO example?

Based on the LIFO method, the last inventory in is the first inventory sold. This means the widgets that cost \$200 sold first. In total, the cost of the widgets under the LIFO method is \$1,200, or five at \$200 and two at \$100. In contrast, using FIFO, the \$100 widgets are sold first, followed by the \$200 widgets.