Upload large file in chunks using C# and VB.Net in ASP.Net

Hi irshadmpct,

Refer below code to upload large file in chunks.

C#

protected void Upload(object sender, EventArgs e)
{
    string fileName = fuUpload.PostedFile.FileName;
    int fileSizeInMB = 1;
    string baseFileName = Path.GetFileName(fileName);
    int bufferSize = fileSizeInMB * (1024 * 1024);
    byte[] fsBuffer = new byte[1024];
    using (FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read))
    {
        int totalFileParts = 0;
        if (fileStream.Length < bufferSize)
        {
            totalFileParts = 1;
        }
        else
        {
            float preciseFileParts = ((float)fileStream.Length / (float)bufferSize);
            totalFileParts = (int)Math.Ceiling(preciseFileParts);
        }

        int filePartCount = 0;
        while (fileStream.Position < fileStream.Length)
        {
            string filePartName = String.Format("{0}.part_{1}.{2}", baseFileName, (filePartCount + 1).ToString(), totalFileParts.ToString());
            filePartName = Path.Combine(Server.MapPath("~/Uploads/"), filePartName);
            using (FileStream fsFilePart = new FileStream(filePartName, FileMode.Create))
            {
                int bytesRemaining = bufferSize;
                int bytesRead = 0;
                while (bytesRemaining > 0 && (bytesRead = fileStream.Read(fsBuffer, 0, Math.Min(bytesRemaining, 1024))) > 0)
                {
                    fsFilePart.Write(fsBuffer, 0, bytesRead);
                    bytesRemaining -= bytesRead;
                }
            }
            filePartCount++;
        }
    }

    string[] partFiles = Directory.GetFiles(Server.MapPath("~/Uploads/"));
    using (FileStream fs = new FileStream(Server.MapPath("~/Uploads/Final/") + fuUpload.FileName, FileMode.Create))
    {
        foreach (string file in partFiles)
        {
            using (FileStream fileChunk = new FileStream(file, FileMode.Open))
            {
                fileChunk.CopyTo(fs);
            }
            File.Delete(file);
        }
    }
}

VB.Net

Protected Sub Upload(ByVal sender As Object, ByVal e As EventArgs)
    Dim fileName As String = fuUpload.PostedFile.FileName
    Dim fileSizeInMB As Integer = 1
    Dim baseFileName As String = Path.GetFileName(fileName)
    Dim bufferSize As Integer = fileSizeInMB * (1024 * 1024)
    Dim fsBuffer As Byte() = New Byte(1023) {}
    Using fileStream As FileStream = New FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read)
        Dim totalFileParts As Integer = 0
        If fileStream.Length < bufferSize Then
            totalFileParts = 1
        Else
            Dim preciseFileParts As Single = (CSng(fileStream.Length) / CSng(bufferSize))
            totalFileParts = CInt(Math.Ceiling(preciseFileParts))
        End If

        Dim filePartCount As Integer = 0
        While fileStream.Position < fileStream.Length
            Dim filePartName As String = String.Format("{0}.part_{1}.{2}", baseFileName, (filePartCount + 1).ToString(), totalFileParts.ToString())
            filePartName = Path.Combine(Server.MapPath("~/Uploads/"), filePartName)
            Using fsFilePart As FileStream = New FileStream(filePartName, FileMode.Create)
                Dim bytesRemaining As Integer = bufferSize
                Dim bytesRead As Integer = 0
                While bytesRemaining > 0 AndAlso (bytesRead = fileStream.Read(fsBuffer, 0, Math.Min(bytesRemaining, 1024))) > 0 > 0
                    fsFilePart.Write(fsBuffer, 0, bytesRead)
                    bytesRemaining -= bytesRead
                End While
            End Using
            filePartCount += 1
        End While
    End Using

    Dim partFiles As String() = Directory.GetFiles(Server.MapPath("~/Uploads/"))
    Using fs As FileStream = New FileStream(Server.MapPath("~/Uploads/Final/") + fuUpload.FileName, FileMode.Create)
        For Each file As String In partFiles
            Using fileChunk As FileStream = New FileStream(file, FileMode.Open)
                fileChunk.CopyTo(fs)
            End Using
            System.IO.File.Delete(file)
        Next
    End Using
End Sub