using System.IO; using System.Text; class Example { static void Main() { // Byte array to write byte[] buffer = Encoding.ASCII.GetBytes("Hello, World!"); // Write byte array directly to output stream using (var writer = new BinaryWriter(File.Open("output.bin", FileMode.Create))) { writer.WriteRaw(buffer, 0, buffer.Length); } } }In this example, we create a byte array containing the ASCII-encoded string "Hello, World!" and write it directly to a binary file using the BinaryWriter class's WriteRaw method. The package/library necessary to use this method is `System.IO`, which provides the `BinaryWriter` class and many other I/O-related classes in the .NET framework.