`Stream`

We use many different derived streams, such as FileStream and MemoryStream. A single C# program often uses many streams together.

In most programs, the Stream type itself isn't usually used directly. It instead is an abstract base class for more derived streams.

Example

Because Stream is an abstract base class for other streams such as FileStream and MemoryStream, you can implicitly cast those streams to Stream types.

Here We introduce a method (the static Print method) that receives a Stream formal parameter.

Note You can pass instances of FileStream and MemoryStream to this method. We use the Stream abstraction to perform certain tasks.

using System;
using System.IO;

class Program
{
    static void Main()
    {
        FileStream stream1 = File.Open("C:\\a", FileMode.Open);
        Print(stream1);

        MemoryStream stream2 = new MemoryStream(new byte[1234]);
        Print(stream2);
    }

    static void Print(Stream stream)
    {
        Console.WriteLine(stream.Length);
        Console.WriteLine(stream.Position);
    }
}5469165
0
1234
0

Because Stream can substitute for many different derived streams, it is sometimes useful to have a field or parameter of type Stream. This can help in some methods.

Tip This means you can avoid having duplicate methods (such as one that receives FileStream and one that receives MemoryStream).

Implementation

The Stream class is an abstract class containing many abstract and virtual methods. These methods are implemented in the classes that inherit from Stream.

Info This helps us understand the architecture of Stream types in the .NET Framework.

Stream is an abstract base class for more useful streams. It is a useful way to deal with different streams at a higher level of abstraction.