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 queue void print_queue(queue< int > q)
{ while (!q.empty())
{
cout << q.front() << " " ;
q.pop();
}
cout << endl;
} // Driver code int 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 Java import 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 Python q = []
# Adds elements {0, 1, 2, 3, 4} to queue for 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 removed removedele = q.pop( 0 )
print ( "removed element-" , removedele)
print (q)
# To view the head of queue head = 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 Java let q = []; // Adds elements {0, 1, 2, 3, 4} to queue for (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 removed let removedele = q.shift(); document.write( "removed element-" + removedele+ "<br>" );
document.write( "[" +q.join( ", " )+ "]<br>" );
// To view the head of queue let 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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