PDF to MemoryStream C#

using System.Web.Mvc;
using System.IO;

public ActionResult ExportPdf()
{
    // Assume pdfAsStream is a MemoryStream containing PDF data
    MemoryStream pdfAsStream = new MemoryStream();

    return new FileStreamResult(pdfAsStream, "application/pdf")
    {
        FileDownloadName = "download.pdf"
    };
}

Imports System.Web.Mvc
Imports System.IO

Public Function ExportPdf() As ActionResult
	' Assume pdfAsStream is a MemoryStream containing PDF data
	Dim pdfAsStream As New MemoryStream()

	Return New FileStreamResult(pdfAsStream, "application/pdf") With {.FileDownloadName = "download.pdf"}
End Function

using System.IO;
using System.Web;

public class PdfHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        // Assume pdfAsStream is a MemoryStream containing PDF data
        MemoryStream pdfAsStream = new MemoryStream();

        context.Response.Clear();
        context.Response.ContentType = "application/octet-stream";
        context.Response.OutputStream.Write(pdfAsStream.ToArray(), 0, (int)pdfAsStream.Length);
        context.Response.Flush();
    }

    public bool IsReusable => false;
}

Imports System.IO
Imports System.Web

Public Class PdfHandler
	Implements IHttpHandler

	Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
		' Assume pdfAsStream is a MemoryStream containing PDF data
		Dim pdfAsStream As New MemoryStream()

		context.Response.Clear()
		context.Response.ContentType = "application/octet-stream"
		context.Response.OutputStream.Write(pdfAsStream.ToArray(), 0, CInt(pdfAsStream.Length))
		context.Response.Flush()
	End Sub

	Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
		Get
			Return False
		End Get
	End Property
End Class