MemoryStream

MemoryStream is a Stream implementation that uses a memory buffer as its backing store. In .NET, System.IO.MemoryStream provides a mutable sequence of bytes that supports reading and writing in a forward or random-access fashion.

Unlike a FileStream, data stored in a MemoryStream resides in managed memory. The stream exposes properties such as Length, Position, and Capacity. Length indicates how many bytes are currently in the stream, Position is the current read/write cursor, and Capacity is the allocated buffer size. The stream supports reading, writing, and seeking, and can be cleared or truncated using SetLength.

Constructors allow creating an empty stream or initializing from an existing byte array. Some constructors permit you to control writability and whether the underlying buffer is externally visible via GetBuffer. The ToArray method returns a copy of the stream contents, while GetBuffer returns the internal array (when permitted).

Typical uses include temporary storage during serialization, buffering data before writing to a file or network, and building up a byte array in memory for processing.

MemoryStream is generally fast because it avoids I/O overhead, but it consumes managed memory and can lead to large memory usage for big streams. It implements IDisposable, so resources are released when the stream is disposed or garbage-collected.