How do you do a deep copy of an object in .NET? 

Important Note

BinaryFormatter has been deprecated, and will no longer be available in .NET after November 2023. See BinaryFormatter Obsoletion Strategy

---

I’ve seen a few different approaches to this, but I use a generic utility method as such:

public static T DeepClone<T>(this T obj)
{
 using (var ms = new MemoryStream())
 {
   var formatter = new BinaryFormatter();
   formatter.Serialize(ms, obj);
   ms.Position = 0;

   return (T) formatter.Deserialize(ms);
 }
}

Notes:

• Your class MUST be marked as [Serializable] for this to work.
• Your source file must include the following code: using System.Runtime.Serialization.Formatters.Binary; using System.IO;