C# Optional Parameters (How It Works For Developers)

Basic Syntax

To define an optional parameter, you assign it a default value in the method's declaration. This default value must be a constant expression. Here’s how you can define a method with one or more optional default parameters in the method definition:

public static void DisplayGreeting(string message, string end = "!")
{
    Console.WriteLine(message + end);
}

public static void DisplayGreeting(string message, string end = "!")
{
    Console.WriteLine(message + end);
}

In the above code snippet, 'end' is an optional parameter with a default parameter value of '!'. This allows the method to be called either with or without providing a second argument.

Method Calls Using Optional Parameters

Here are two ways to call the above method:

static void Main()
{
    DisplayGreeting("Hello"); // Outputs: Hello!
    DisplayGreeting("Hello", "?"); // Outputs: Hello?
}

static void Main()
{
    DisplayGreeting("Hello"); // Outputs: Hello!
    DisplayGreeting("Hello", "?"); // Outputs: Hello?
}

The first call omits the second argument, using the default value. The second call provides a specific value, overriding the default.

Example of Using Named Parameters

// Named parameters
public static void ConfigureDevice(string deviceName, bool enableLogging = false, int timeout = 30)
{
    Console.WriteLine($"Configuring {deviceName}: Logging={(enableLogging ? "On" : "Off")}, Timeout={timeout}s");
}

// Named parameters
public static void ConfigureDevice(string deviceName, bool enableLogging = false, int timeout = 30)
{
    Console.WriteLine($"Configuring {deviceName}: Logging={(enableLogging ? "On" : "Off")}, Timeout={timeout}s");
}

You can use named parameters to specify values out of order or to skip optional parameters.

static void Main()
{
    ConfigureDevice("Router", timeout: 60);
}

static void Main()
{
    ConfigureDevice("Router", timeout: 60);
}

This call uses an optional argument to specify a value for a timeout while using the default for enableLogging.

Code Example

public static void CreateProfile(string firstName, string lastName, int age = 25, string city = "Unknown")
{
    Console.WriteLine($"Name: {firstName} {lastName}, Age: {age}, City: {city}");
}

public static void CreateProfile(string firstName, string lastName, int age = 25, string city = "Unknown")
{
    Console.WriteLine($"Name: {firstName} {lastName}, Age: {age}, City: {city}");
}

Calling the Method

static void Main()
{
    CreateProfile("John", "Doe"); // Uses default age and city
    CreateProfile("Jane", "Doe", 30, "New York"); // Specifies all parameters
}

static void Main()
{
    CreateProfile("John", "Doe"); // Uses default age and city
    CreateProfile("Jane", "Doe", 30, "New York"); // Specifies all parameters
}

This flexibility to omit arguments allows the same method to be used in different contexts without needing multiple overloads.

Correct Use of Default Values

public static void SendEmail(string address, string subject = "No Subject", string body = "")
{
    Console.WriteLine($"Sending email to {address}\nSubject: {subject}\nBody: {body}");
}

public static void SendEmail(string address, string subject = "No Subject", string body = "")
{
    Console.WriteLine($"Sending email to {address}\nSubject: {subject}\nBody: {body}");
}

Comparison Through Code

Overloaded methods might look like this:

// Method overloading
public static void Alert(string message)
{
    Console.WriteLine(message);
}

public static void Alert(string message, bool urgent)
{
    if (urgent)
        Console.WriteLine("Urgent: " + message);
    else
        Console.WriteLine(message);
}

// Method overloading
public static void Alert(string message)
{
    Console.WriteLine(message);
}

public static void Alert(string message, bool urgent)
{
    if (urgent)
        Console.WriteLine("Urgent: " + message);
    else
        Console.WriteLine(message);
}

An equivalent method using optional parameters:

public static void Alert(string message, bool urgent = false)
{
    if (urgent)
        Console.WriteLine("Urgent: " + message);
    else
        Console.WriteLine(message);
}

public static void Alert(string message, bool urgent = false)
{
    if (urgent)
        Console.WriteLine("Urgent: " + message);
    else
        Console.WriteLine(message);
}

Code Example

Here's an example demonstrating how you can use IronPDF along with C# optional parameters to generate a customized PDF report from a simple HTML template, potentially adjusting details like the title and whether to include certain report sections:

using IronPdf;
using System;

public class PdfReportGenerator
{
    // Method to generate PDF with optional parameters
    public static void CreatePdfReport(string htmlContent, string filePath = "Report.pdf", bool includeCharts = true, string reportTitle = "Monthly Report")
    {
        // Optional parameters allow customization of the report's title and content dynamically
        var renderer = new ChromePdfRenderer();
        // Customize the PDF document
        renderer.RenderingOptions.TextHeader.CenterText = reportTitle;
        renderer.RenderingOptions.TextFooter.CenterText = "Generated on " + DateTime.Now.ToString("dd-MM-yyyy");
        renderer.RenderingOptions.MarginTop = 50;  // Set the top margin
        renderer.RenderingOptions.MarginBottom = 50;  // Set the bottom margin
        if (!includeCharts)
        {
            // Modify HTML content to remove chart sections if not included
            htmlContent = htmlContent.Replace("<div class='charts'></div>", "");
        }
        // Render the HTML to PDF
        PdfDocument pdf = renderer.RenderHtmlAsPdf(htmlContent);
        // Save the generated PDF to a file
        pdf.SaveAs(filePath);
        Console.WriteLine($"PDF report has been created at {filePath}");
    }

    static void Main()
    {
        License.LicenseKey = "License-Key"; // Specify the license key if required
        string htmlTemplate = @"
        <html>
        <head>
            <title>Monthly Report</title>
        </head>
        <body>
            <h1>Monthly Performance Report</h1>
            <p>This section contains text describing the overall performance for the month.</p>
            <div class='charts'>
                <h2>Sales Charts</h2>

            </div>
        </body>
        </html>";

        // Call the CreatePdfReport method with different parameters
        CreatePdfReport(htmlTemplate, "BasicReport.pdf", false, "Basic Monthly Report");
        CreatePdfReport(htmlTemplate, "FullReport.pdf", true, "Detailed Monthly Report");
    }
}

using IronPdf;
using System;

public class PdfReportGenerator
{
    // Method to generate PDF with optional parameters
    public static void CreatePdfReport(string htmlContent, string filePath = "Report.pdf", bool includeCharts = true, string reportTitle = "Monthly Report")
    {
        // Optional parameters allow customization of the report's title and content dynamically
        var renderer = new ChromePdfRenderer();
        // Customize the PDF document
        renderer.RenderingOptions.TextHeader.CenterText = reportTitle;
        renderer.RenderingOptions.TextFooter.CenterText = "Generated on " + DateTime.Now.ToString("dd-MM-yyyy");
        renderer.RenderingOptions.MarginTop = 50;  // Set the top margin
        renderer.RenderingOptions.MarginBottom = 50;  // Set the bottom margin
        if (!includeCharts)
        {
            // Modify HTML content to remove chart sections if not included
            htmlContent = htmlContent.Replace("<div class='charts'></div>", "");
        }
        // Render the HTML to PDF
        PdfDocument pdf = renderer.RenderHtmlAsPdf(htmlContent);
        // Save the generated PDF to a file
        pdf.SaveAs(filePath);
        Console.WriteLine($"PDF report has been created at {filePath}");
    }

    static void Main()
    {
        License.LicenseKey = "License-Key"; // Specify the license key if required
        string htmlTemplate = @"
        <html>
        <head>
            <title>Monthly Report</title>
        </head>
        <body>
            <h1>Monthly Performance Report</h1>
            <p>This section contains text describing the overall performance for the month.</p>
            <div class='charts'>
                <h2>Sales Charts</h2>

            </div>
        </body>
        </html>";

        // Call the CreatePdfReport method with different parameters
        CreatePdfReport(htmlTemplate, "BasicReport.pdf", false, "Basic Monthly Report");
        CreatePdfReport(htmlTemplate, "FullReport.pdf", true, "Detailed Monthly Report");
    }
}

Here is the FullReport PDF file preview:

The CreatePdfReport method in the code example is structured to generate PDF documents from HTML content, offering flexibility with optional parameters like the file path, the inclusion of charts, and the report title. This design allows the method to adapt to different reporting needs with minor code adjustments. Within the method, IronPDF settings are adjusted to include custom headers and footers in the PDF, which are set to display the report title and the date the report was generated.

Margins are also configured to improve the document's visual layout. Depending on whether the includeCharts parameter is true or false, the HTML content is dynamically modified to either include or exclude chart visuals. Finally, the potentially modified HTML is converted into a PDF and saved to a specified location. This example demonstrates how optional parameters can significantly streamline the process of creating tailored PDF reports.