FIFO is an abbreviation for first in, first out. It is a method for handling data structures where the first element is processed first and the newest element is processed last.
Real-life example:
In this example, following things are to be considered:
- There is a ticket counter where people come, take tickets and go.
- People enter a line (queue) to get to the Ticket Counter in an organized manner.
- The person to enter the queue first, will get the ticket first and leave the queue.
- The person entering the queue next will get the ticket after the person in front of him
- In this way, the person entering the queue last will the tickets last
- Therefore, the First person to enter the queue gets the ticket first and the Last person to enter the queue gets the ticket last.
This is known as First-In-First-Out approach or FIFO.
Where is FIFO used:
- Data Structures:
- Certain data structures like Queue and other variants of Queue uses FIFO approach for processing data.
- Disk scheduling:
- Disk controllers can use the FIFO as a disk scheduling algorithm to determine the order in which to service disk I/O requests.
- Communications and networking”
- Communication network bridges, switches and routers used in computer networks use FIFOs to hold data packets en route to their next destination.
Program Examples for FIFO
Program 1: Queue
C++
// C++ program to demonstrate // working of FIFO // using Queue interface in C++#include<bits/stdc++.h>using namespace std;// print the elements of queuevoid print_queue(queue<int> q){ while (!q.empty()) { cout << q.front() << " "; q.pop(); } cout << endl;}// Driver codeint main() { queue<int> q ; // Adds elements {0, 1, 2, 3, 4} to queue for (int i = 0; i < 5; i++) q.push(i); // Display contents of the queue. cout << "Elements of queue-"; print_queue(q); // To remove the head of queue. // In this the oldest element '0' will be removed int removedele = q.front(); q.pop(); cout << "removed element-" << removedele << endl; print_queue(q); // To view the head of queue int head = q.front(); cout << "head of queue-" << head << endl; // Rest all methods of collection interface, // Like size and contains can be used with this // implementation. int size = q.size(); cout << "Size of queue-" << size; return 0;} // This code is contributed by Arnab Kundu |
Java
// Java program to demonstrate// working of FIFO// using Queue interface in Javaimport java.util.LinkedList;import java.util.Queue;public class QueueExample { public static void main(String[] args) { Queue<Integer> q = new LinkedList<>(); // Adds elements {0, 1, 2, 3, 4} to queue for (int i = 0; i < 5; i++) q.add(i); // Display contents of the queue. System.out.println("Elements of queue-" + q); // To remove the head of queue. // In this the oldest element '0' will be removed int removedele = q.remove(); System.out.println("removed element-" + removedele); System.out.println(q); // To view the head of queue int head = q.peek(); System.out.println("head of queue-" + head); // Rest all methods of collection interface, // Like size and contains can be used with this // implementation. int size = q.size(); System.out.println("Size of queue-" + size); }} |
Python3
# Python program to demonstrate# working of FIFO# using Queue interface in Pythonq = []# Adds elements {0, 1, 2, 3, 4} to queuefor i in range(5): q.append(i)# Display contents of the queue.print("Elements of queue-" , q)# To remove the head of queue.# In this the oldest element '0' will be removedremovedele = q.pop(0)print("removed element-" , removedele)print(q)# To view the head of queuehead = q[0]print("head of queue-" , head)# Rest all methods of collection interface,# Like size and contains can be used with this# implementation.size = len(q)print("Size of queue-" , size)# This code is contributed by patel2127. |
C#
// C# program to demonstrate // working of FIFO using System;using System.Collections.Generic;public class QueueExample { public static void Main(String[] args) { Queue<int> q = new Queue<int>(); // Adds elements {0, 1, 2, 3, 4} to queue for (int i = 0; i < 5; i++) q.Enqueue(i); // Display contents of the queue. Console.Write("Elements of queue-"); foreach(int s in q) Console.Write(s + " "); // To remove the head of queue. // In this the oldest element '0' will be removed int removedele = q.Dequeue(); Console.Write("\nremoved element-" + removedele + "\n"); foreach(int s in q) Console.Write(s + " "); // To view the head of queue int head = q.Peek(); Console.Write("\nhead of queue-" + head); // Rest all methods of collection interface, // Like size and contains can be used with this // implementation. int size = q.Count; Console.WriteLine("\nSize of queue-" + size); } } // This code has been contributed by 29AjayKumar |
Javascript
<script>// JavaScript program to demonstrate// working of FIFO// using Queue interface in Javalet q = [];// Adds elements {0, 1, 2, 3, 4} to queuefor (let i = 0; i < 5; i++) q.push(i);// Display contents of the queue.document.write("Elements of queue-[" + q.join(", ")+"]<br>");// To remove the head of queue.// In this the oldest element '0' will be removedlet removedele = q.shift();document.write("removed element-" + removedele+"<br>");document.write("["+q.join(", ")+"]<br>");// To view the head of queuelet head = q[0];document.write("head of queue-" + head+"<br>");// Rest all methods of collection interface,// Like size and contains can be used with this// implementation.let size = q.length;document.write("Size of queue-" + size+"<br>");// This code is contributed by avanitrachhadiya2155</script> |
Output
Elements of queue-0 1 2 3 4 removed element-0 1 2 3 4 head of queue-1 Size of queue-4
Complexities Analysis:
- Time Complexity: O(N)
- Space Complexity: O(N)
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