Imports System.IO
 
Public Class Form1
 
    Dim input_filepath As String = "C:\Test.txt"
    Dim output_filepath As String = "C:\Test_New.txt"
    Dim input As New FileStream(input_filepath, FileMode.Open, FileAccess.ReadWrite)
    Dim output As New FileStream(output_filepath, FileMode.Create, FileAccess.ReadWrite)
 
    Public Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        CopyStream(input, output)
        ' For Testing:
        'If New IO.FileInfo(output_filepath).Length = 0 Then IO.File.Delete(output_filepath) : Application.Exit() Else Process.Start("Notepad", output_filepath)
    End Sub
 
    Public Sub CopyStream(ByVal inputStream As Stream, ByVal outputStream As Stream)
 
        Dim buffer = New Byte(1025) {}
        Dim bytesRead As Integer = 0
 
        While (bytesRead = inputStream.Read(buffer, 0, buffer.Length)) > 0
            outputStream.Write(buffer, 0, bytesRead)
        End While
 
        inputStream.Flush() : outputStream.Flush()
        inputStream.Close() : outputStream.Close()
 
    End Sub
 
End Class

using System;
using System.IO;
 
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            CopyMyFiles();
            Console.WriteLine("DONE!");
            Console.ReadLine();
        }
 
        private static void CopyMyFiles()
        {
            string input_filepath = "Test.txt";
            string output_filepath = "Test_New.txt";
 
            var input = new System.IO.FileStream(input_filepath, FileMode.Open, FileAccess.ReadWrite);
            var output = new System.IO.FileStream(output_filepath, FileMode.Create, FileAccess.ReadWrite);
 
            CopyStream(input, output);
        }
 
        public static void CopyStream(Stream inputStream, Stream outputStream)
        {
            byte[] buffer = new byte[1025];
            int bytesRead = 0;
 
            while ((bytesRead = inputStream.Read(buffer, 0, buffer.Length)) > 0)
            {
                outputStream.Write(buffer, 0, bytesRead);
            }
 
            outputStream.Flush();
            inputStream.Close();
            outputStream.Close();
        }
    }
}