.NET HELP

C# Queue (How it Works For Developers)

ByChipego Kalinda

January 4, 2024

Updated June 22, 2025

1. Introduction

In the realm of programming, efficient data handling is a cornerstone of successful software development. One essential data structure that plays a crucial role in managing and organizing information is the queue. In the context of C#, a powerful and versatile programming language, the C# Queue stands out as a fundamental tool for managing data sequentially. To know more about the Queues in C#, here are the recommended articles on Queues in C# and Generic Queue class in .NET.

A queue follows the First-In-First-Out (FIFO) principle, where the first element added is the first one to be removed. This characteristic makes it particularly useful in scenarios where data or objects need to be processed in a specific order, such as handling tasks in a systematic way or managing requests in a web server.

In this article, we will use the C# PDF Library IronPDF with the C# Queue.

2. Types and Uses of C# Queue

2.1. Standard Queue

The standard queue in C# is a generic class that allows developers to create a queue of any data type. It provides methods like Enqueue for adding elements to the end of the queue and Dequeue for removing elements from the front. This type of queue is widely used in scenarios where data processing follows a strict order, ensuring fairness in resource allocation.

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {   
        // Create an empty queue
        Queue<int> standardQueue = new Queue<int>();

        // Enqueue elements into the queue
        standardQueue.Enqueue(10);
        standardQueue.Enqueue(20);
        standardQueue.Enqueue(30);

        // Dequeue elements from the queue until it is empty
        while (standardQueue.Count > 0)
        {
            int element = standardQueue.Dequeue();
            Console.WriteLine($"Dequeued: {element}");
        }
    }
}

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {   
        // Create an empty queue
        Queue<int> standardQueue = new Queue<int>();

        // Enqueue elements into the queue
        standardQueue.Enqueue(10);
        standardQueue.Enqueue(20);
        standardQueue.Enqueue(30);

        // Dequeue elements from the queue until it is empty
        while (standardQueue.Count > 0)
        {
            int element = standardQueue.Dequeue();
            Console.WriteLine($"Dequeued: {element}");
        }
    }
}

Imports System
Imports System.Collections.Generic

Friend Class Program
	Shared Sub Main()
		' Create an empty queue
		Dim standardQueue As New Queue(Of Integer)()

		' Enqueue elements into the queue
		standardQueue.Enqueue(10)
		standardQueue.Enqueue(20)
		standardQueue.Enqueue(30)

		' Dequeue elements from the queue until it is empty
		Do While standardQueue.Count > 0
			Dim element As Integer = standardQueue.Dequeue()
			Console.WriteLine($"Dequeued: {element}")
		Loop
	End Sub
End Class

$vbLabelText $csharpLabel

Output

C# Queue (How it Works For Developers): Figure 1 - OUTPUT: Standard Queue

2.2. Priority Queue

In certain situations, prioritizing elements in the queue becomes crucial. C# does not have a built-in priority queue, but developers can implement one by using a sorted collection or a custom data structure. This type of queue is beneficial when certain elements need to be processed ahead of others based on specific criteria, such as urgency or importance.

using System;
using System.Collections.Generic;

class Program
{    
    static void Main()
    {
        // Create a priority queue using a sorted set to store elements in order
        SortedSet<int> priorityQueue = new SortedSet<int>();

        // Add elements to the priority queue
        priorityQueue.Add(30);
        priorityQueue.Add(10);
        priorityQueue.Add(20);

        // Dequeue elements from the priority queue based on their priority
        while (priorityQueue.Count > 0)
        {
            // Access the minimum element (highest priority for this example)
            int element = priorityQueue.Min;
            // Remove the element from the queue
            priorityQueue.Remove(element);
            Console.WriteLine($"Priority Queue Dequeued: {element}");
        }
    }
}

using System;
using System.Collections.Generic;

class Program
{    
    static void Main()
    {
        // Create a priority queue using a sorted set to store elements in order
        SortedSet<int> priorityQueue = new SortedSet<int>();

        // Add elements to the priority queue
        priorityQueue.Add(30);
        priorityQueue.Add(10);
        priorityQueue.Add(20);

        // Dequeue elements from the priority queue based on their priority
        while (priorityQueue.Count > 0)
        {
            // Access the minimum element (highest priority for this example)
            int element = priorityQueue.Min;
            // Remove the element from the queue
            priorityQueue.Remove(element);
            Console.WriteLine($"Priority Queue Dequeued: {element}");
        }
    }
}

Imports System
Imports System.Collections.Generic

Friend Class Program
	Shared Sub Main()
		' Create a priority queue using a sorted set to store elements in order
		Dim priorityQueue As New SortedSet(Of Integer)()

		' Add elements to the priority queue
		priorityQueue.Add(30)
		priorityQueue.Add(10)
		priorityQueue.Add(20)

		' Dequeue elements from the priority queue based on their priority
		Do While priorityQueue.Count > 0
			' Access the minimum element (highest priority for this example)
			Dim element As Integer = AddressOf priorityQueue.Min
			' Remove the element from the queue
			priorityQueue.Remove(element)
			Console.WriteLine($"Priority Queue Dequeued: {element}")
		Loop
	End Sub
End Class

$vbLabelText $csharpLabel

C# Queue (How it Works For Developers): Figure 2 - OUTPUT: Priority Queue

2.3. Circular Queue

A circular queue is a variant where the last element is connected to the first, creating a circular structure. This can be advantageous in scenarios where the queue has a fixed size, and old queue elements need to be replaced by new ones in a cyclic manner. Implementing a circular queue in C# can optimize memory usage and ensure efficient data processing.

using System;

// CircularQueue class to implement a fixed-size circular queue
class CircularQueue
{
    private int[] array;
    private int front, rear, size;

    public CircularQueue(int size)
    {
        this.size = size;
        array = new int[size];
        front = rear = -1;
    }

    // Enqueue method to add an element to the circular queue
    public void Enqueue(int item)
    {
        if ((front == 0 && rear == size - 1) || (rear == (front - 1) % (size - 1)))
        {
            Console.WriteLine("Queue is full");
            return;
        }
        else if (front == -1)  // Initial insertion case
        {
            front = rear = 0;
            array[rear] = item;
        }
        else if (rear == size - 1 && front != 0)  // Wrap around
        {
            rear = 0;
            array[rear] = item;
        }
        else  // Normal case
        {
            rear++;
            array[rear] = item;
        }
    }

    // Dequeue method to remove an element from the circular queue
    public int Dequeue()
    {
        if (front == -1)  // Queue is empty case
        {
            Console.WriteLine("Queue is empty");
            return -1;
        }

        int item = array[front];
        array[front] = -1;

        if (front == rear)  // Single element case
            front = rear = -1;
        else if (front == size - 1)  // Wrap around
            front = 0;
        else  // Normal case
            front++;

        return item;
    }
}

class Program
{
    static void Main()
    {   
        // Create a circular queue with a specified initial capacity
        CircularQueue circularQueue = new CircularQueue(5);

        // Enqueue elements
        circularQueue.Enqueue(10);
        circularQueue.Enqueue(20);
        circularQueue.Enqueue(30);

        // Dequeue elements
        Console.WriteLine($"Circular Queue Dequeued: {circularQueue.Dequeue()}");
        Console.WriteLine($"Circular Queue Dequeued: {circularQueue.Dequeue()}");
    }
}

using System;

// CircularQueue class to implement a fixed-size circular queue
class CircularQueue
{
    private int[] array;
    private int front, rear, size;

    public CircularQueue(int size)
    {
        this.size = size;
        array = new int[size];
        front = rear = -1;
    }

    // Enqueue method to add an element to the circular queue
    public void Enqueue(int item)
    {
        if ((front == 0 && rear == size - 1) || (rear == (front - 1) % (size - 1)))
        {
            Console.WriteLine("Queue is full");
            return;
        }
        else if (front == -1)  // Initial insertion case
        {
            front = rear = 0;
            array[rear] = item;
        }
        else if (rear == size - 1 && front != 0)  // Wrap around
        {
            rear = 0;
            array[rear] = item;
        }
        else  // Normal case
        {
            rear++;
            array[rear] = item;
        }
    }

    // Dequeue method to remove an element from the circular queue
    public int Dequeue()
    {
        if (front == -1)  // Queue is empty case
        {
            Console.WriteLine("Queue is empty");
            return -1;
        }

        int item = array[front];
        array[front] = -1;

        if (front == rear)  // Single element case
            front = rear = -1;
        else if (front == size - 1)  // Wrap around
            front = 0;
        else  // Normal case
            front++;

        return item;
    }
}

class Program
{
    static void Main()
    {   
        // Create a circular queue with a specified initial capacity
        CircularQueue circularQueue = new CircularQueue(5);

        // Enqueue elements
        circularQueue.Enqueue(10);
        circularQueue.Enqueue(20);
        circularQueue.Enqueue(30);

        // Dequeue elements
        Console.WriteLine($"Circular Queue Dequeued: {circularQueue.Dequeue()}");
        Console.WriteLine($"Circular Queue Dequeued: {circularQueue.Dequeue()}");
    }
}

Imports System

' CircularQueue class to implement a fixed-size circular queue
Friend Class CircularQueue
	Private array() As Integer
	Private front, rear, size As Integer

	Public Sub New(ByVal size As Integer)
		Me.size = size
		array = New Integer(size - 1){}
'INSTANT VB WARNING: An assignment within expression was extracted from the following statement:
'ORIGINAL LINE: front = rear = -1;
		rear = -1
		front = rear
	End Sub

	' Enqueue method to add an element to the circular queue
	Public Sub Enqueue(ByVal item As Integer)
		If (front = 0 AndAlso rear = size - 1) OrElse (rear = (front - 1) Mod (size - 1)) Then
			Console.WriteLine("Queue is full")
			Return
		ElseIf front = -1 Then ' Initial insertion case
'INSTANT VB WARNING: An assignment within expression was extracted from the following statement:
'ORIGINAL LINE: front = rear = 0;
			rear = 0
			front = rear
			array(rear) = item
		ElseIf rear = size - 1 AndAlso front <> 0 Then ' Wrap around
			rear = 0
			array(rear) = item
		Else ' Normal case
			rear += 1
			array(rear) = item
		End If
	End Sub

	' Dequeue method to remove an element from the circular queue
	Public Function Dequeue() As Integer
		If front = -1 Then ' Queue is empty case
			Console.WriteLine("Queue is empty")
			Return -1
		End If

		Dim item As Integer = array(front)
		array(front) = -1

		If front = rear Then ' Single element case
'INSTANT VB WARNING: An assignment within expression was extracted from the following statement:
'ORIGINAL LINE: front = rear = -1;
			rear = -1
			front = rear
		ElseIf front = size - 1 Then ' Wrap around
			front = 0
		Else ' Normal case
			front += 1
		End If

		Return item
	End Function
End Class

Friend Class Program
	Shared Sub Main()
		' Create a circular queue with a specified initial capacity
		Dim circularQueue As New CircularQueue(5)

		' Enqueue elements
		circularQueue.Enqueue(10)
		circularQueue.Enqueue(20)
		circularQueue.Enqueue(30)

		' Dequeue elements
		Console.WriteLine($"Circular Queue Dequeued: {circularQueue.Dequeue()}")
		Console.WriteLine($"Circular Queue Dequeued: {circularQueue.Dequeue()}")
	End Sub
End Class

$vbLabelText $csharpLabel

C# Queue (How it Works For Developers): Figure 3 - OUTPUT: Circular Queue

3. Introducing IronPDF in C#

As we delve into the functionalities and applications of the C# Queue, it's essential to explore how it can be seamlessly integrated into real-world applications. One such powerful tool that enhances C# capabilities is IronPDF.

IronPDF is a C# library that simplifies the creation, manipulation, and rendering of PDF documents. Its intuitive API allows developers to generate PDFs from HTML, ASPX, or even plain text. With IronPDF, the process of incorporating C# Queue into a PDF-generating application becomes streamlined and efficient.

3.1. Using C# Queue with IronPDF Code

Let's take a closer look at how the C# Queue can be utilized in conjunction with IronPDF to create dynamic and organized PDF documents. Consider a scenario where a web application needs to generate a PDF report based on user inputs and requests.

using IronPdf;
using System;
using System.Collections.Generic;

class PdfGenerator
{
    static void Main()
    {
        // Create a C# Queue to store user requests
        Queue<string> userRequests = new Queue<string>();

        // Simulate user requests being added to the queue
        userRequests.Enqueue("Generate PDF for User 1");
        userRequests.Enqueue("Generate PDF for User 2");
        userRequests.Enqueue("Generate PDF for User 3");

        // Process requests and generate PDFs
        while (userRequests.Count > 0)
        {
            string request = userRequests.Dequeue();
            GeneratePdf(request);
        }
    }

    // Method to generate a PDF file using IronPDF
    static void GeneratePdf(string userRequest)
    {
        // Use IronPDF to generate PDF based on user request
        var Renderer = new HtmlToPdf();

        // Render the provided HTML content as a PDF
        var PDF = Renderer.RenderHtmlAsPdf($"<h1>{userRequest}</h1>");

        // Save the generated PDF with the request name as file name
        PDF.SaveAs($"{userRequest.Replace(" ", "_")}.pdf");
    }
}

using IronPdf;
using System;
using System.Collections.Generic;

class PdfGenerator
{
    static void Main()
    {
        // Create a C# Queue to store user requests
        Queue<string> userRequests = new Queue<string>();

        // Simulate user requests being added to the queue
        userRequests.Enqueue("Generate PDF for User 1");
        userRequests.Enqueue("Generate PDF for User 2");
        userRequests.Enqueue("Generate PDF for User 3");

        // Process requests and generate PDFs
        while (userRequests.Count > 0)
        {
            string request = userRequests.Dequeue();
            GeneratePdf(request);
        }
    }

    // Method to generate a PDF file using IronPDF
    static void GeneratePdf(string userRequest)
    {
        // Use IronPDF to generate PDF based on user request
        var Renderer = new HtmlToPdf();

        // Render the provided HTML content as a PDF
        var PDF = Renderer.RenderHtmlAsPdf($"<h1>{userRequest}</h1>");

        // Save the generated PDF with the request name as file name
        PDF.SaveAs($"{userRequest.Replace(" ", "_")}.pdf");
    }
}

Imports IronPdf
Imports System
Imports System.Collections.Generic

Friend Class PdfGenerator
	Shared Sub Main()
		' Create a C# Queue to store user requests
		Dim userRequests As New Queue(Of String)()

		' Simulate user requests being added to the queue
		userRequests.Enqueue("Generate PDF for User 1")
		userRequests.Enqueue("Generate PDF for User 2")
		userRequests.Enqueue("Generate PDF for User 3")

		' Process requests and generate PDFs
		Do While userRequests.Count > 0
			Dim request As String = userRequests.Dequeue()
			GeneratePdf(request)
		Loop
	End Sub

	' Method to generate a PDF file using IronPDF
	Private Shared Sub GeneratePdf(ByVal userRequest As String)
		' Use IronPDF to generate PDF based on user request
		Dim Renderer = New HtmlToPdf()

		' Render the provided HTML content as a PDF
		Dim PDF = Renderer.RenderHtmlAsPdf($"<h1>{userRequest}</h1>")

		' Save the generated PDF with the request name as file name
		PDF.SaveAs($"{userRequest.Replace(" ", "_")}.pdf")
	End Sub
End Class

$vbLabelText $csharpLabel

In this example, a C# Queue (userRequests) is used to store user requests for PDF generation. The GeneratePdf method takes a user request, utilizes IronPDF to convert HTML content to a PDF document, and saves the generated PDF file with a relevant name.

This integration method also showcases the synergy between C# Queue and IronPDF, where the orderly processing of user requests results in the systematic creation of PDF documents.

3.2. Output #1

C# Queue (How it Works For Developers): Figure 4 - OUTPUT 1: Generate PDF using IronPDF and C# Queue

3.3. Output #2

C# Queue (How it Works For Developers): Figure 5 - OUTPUT 2: Generate PDF using IronPDF and C# Queue

3.4. Output #3

C# Queue (How it Works For Developers): Figure 6 - OUTPUT 3: Generate PDF using IronPDF and C# Queue

4. Conclusion

In conclusion, the C# Queue proves to be a valuable asset in managing and processing data sequentially. Its adherence to the FIFO principle makes it suitable for a wide range of applications, from task scheduling to request handling in web servers. When combined with powerful libraries like IronPDF, the C# Queue becomes even more potent, allowing developers to create organized and dynamic PDF documents efficiently.

Understanding the nuances of C# Queue and exploring its integration with tools like IronPDF empowers developers to design robust and efficient solutions for data management and processing. As technology continues to evolve, the synergy between fundamental data structures like the C# Queue and innovative libraries will play a pivotal role in shaping the landscape of software development.

For licensing information, visit IronPDF licensing details. To know more about the HTML to PDF conversion, visit the HTML to PDF Conversion Tutorial.

Frequently Asked Questions

What is a C# Queue?

A C# Queue is a data structure that follows the First-In-First-Out (FIFO) principle, where the first element added is the first one to be removed. It is useful for managing and organizing data in a sequential manner.

How does the standard Queue in C# work?

The standard Queue in C# is a generic class that allows developers to create a queue of any data type. It provides methods like 'Enqueue' for adding elements to the end of the queue and 'Dequeue' for removing elements from the front, ensuring fairness in resource allocation.

Can you implement a priority queue in C#?

Yes, while C# does not have a built-in priority queue, developers can implement one using a sorted collection or a custom data structure to prioritize elements based on specific criteria.

What is a circular queue in C#?

A circular queue is a variant of the queue where the last element is connected to the first, creating a circular structure. It is useful when the queue has a fixed size and old elements need to be replaced by new ones in a cyclic manner.

How can C# Queue be used to manage PDF generation requests?

C# Queue can be used to manage user requests for PDF generation by storing requests in a queue. Developers can process each request in order and generate dynamic PDF documents using the features of IronPDF.

What is IronPDF?

IronPDF is a C# library that simplifies the creation, manipulation, and rendering of PDF documents. It allows developers to generate PDFs from HTML, ASPX, or plain text, enhancing C# capabilities.

What are some real-world applications of C# Queue?

C# Queue is suitable for applications like task scheduling, handling requests in web servers, and any scenario requiring data or objects to be processed in a specific order.

How do you create a standard queue in C#?

To create a standard queue in C#, use the Queue class from System.Collections.Generic. You can enqueue elements using 'Enqueue' and dequeue them using 'Dequeue' in a FIFO manner.

What are the benefits of using a circular queue?

Circular queues optimize memory usage and ensure efficient data processing, especially in scenarios with a fixed-size queue where elements are replaced cyclically.

What is the FIFO principle in queuing?

FIFO stands for First-In-First-Out, a principle where the first element added to the queue is the first one to be removed. This ensures a systematic order of processing data.

Chipego Kalinda

Chat with engineering team now

Software Engineer

Chipego has a natural skill for listening that helps him to comprehend customer issues, and offer intelligent solutions. He joined the Iron Software team in 2023, after studying a Bachelor of Science in Information Technology. IronPDF and IronOCR are the two products Chipego has been focusing on, but his knowledge of all products is growing daily, as he finds new ways to support customers. He enjoys how collaborative life is at Iron Software, with team members from across the company bringing their varied experience to contribute to effective, innovative solutions. When Chipego is away from his desk, he can often be found enjoying a good book or playing football.

Hangfire .NET Core (How It Works For Developers)

C# Case Statement (How it Works For Developers)