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What are LIFO and FILO? Easy-to-understand explanation of basic concepts of data structures

Explanation of IT Terms

What are LIFO and FILO?

LIFO and FILO are two fundamental concepts in data structures. They stand for “Last In, First Out” and “First In, Last Out,” respectively. Both LIFO and FILO are strategies that describe how elements are accessed and processed within a data structure.

In LIFO, the last element added to the data structure is the first one to be removed. It works like a stack of items where you pile new elements on top, and when you need to retrieve an element, you take the topmost one. Think of it as a stack of plates in a cafeteria. The last plate you put on top is the first one you can grab.

On the other hand, in FILO, the first element added to the data structure is the last one to be removed. It is commonly used in queues, where elements join at the end and are removed from the front. Imagine a line of people waiting at a ticket booth. The first person to join the line is the last one to get their ticket.

LIFO (Last In, First Out) Example:

Let’s say you are writing a program to process a series of commands. Each command can be stored in a LIFO data structure, known as a stack. As new commands come in, they are pushed onto the stack. When it’s time to process a command, the topmost command is taken from the stack and executed. This ensures that the most recent command is always the first to be processed. A practical example of LIFO is the functioning of the undo feature in many text editing programs. When you undo an action, the program retrieves the most recent action from the stack and reverses it.

FILO (First In, Last Out) Example:

Consider an online order fulfillment system that utilizes a queue to manage incoming orders. Each new order is added to the end of the queue, while the orders are processed from the front of the queue. This ensures that the oldest order is always the first one to be processed. This order of processing is a prime example of the FILO concept.

In conclusion, LIFO and FILO are two strategies for organizing and processing data in data structures. LIFO structures prioritize the most recently added elements, while FILO structures prioritize the oldest elements. Understanding these concepts is essential in designing efficient programs and systems that handle data in a structured and logical manner.

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