Updated: September 2010
Creates a shallow copy of the current Object.
Assembly: mscorlib (in mscorlib.dll)
The method creates a shallow copy by creating a new object, and then copying the nonstatic fields of the current object to the new object. If a field is a value type, a bit-by-bit copy of the field is performed. If a field is a reference type, the reference is copied but the referred object is not; therefore, the original object and its clone refer to the same object.
For example, consider an object called X that references objects A and B. Object B, in turn, references object C. A shallow copy of X creates new object X2 that also references objects A and B. In contrast, a deep copy of X creates a new object X2 that references the new objects A2 and B2, which are copies of A and B. B2, in turn, references the new object C2, which is a copy of C. The example illustrates the difference between a shallow and a deep copy operation.
There are numerous ways to implement a deep copy operation if the shallow copy operation performed by the method does not meet your needs. These include the following:
Call a class constructor of the object to be copied to create a second object with property values taken from the first object. This assumes that the values of an object are entirely defined by its class constructor.
Call the method to create a shallow copy of an object, and then assign new objects whose values are the same as the original object to any properties or fields whose values are reference types. The DeepCopy method in the example illustrates this approach.
Serialize the object to be deep copied, and then restore the serialized data to a different object variable.
Use reflection with recursion to perform the deep copy operation.
The following example illustrates the method. It defines a ShallowCopy method that calls the method to perform a shallow copy operation on a Person object. It also defines a DeepCopy method that performs a deep copy operation on a Person object.
In this example, the Person.IdInfo property returns an IdInfo object. As the output from the example shows, when a Person object is cloned by calling the method, the cloned Person object is an independent copy of the original object, except that they share the same Person.IdInfo object reference. As a result, modifying the clone's Person.IdInfo property changes the original object's Person.IdInfo property. On the other hand, when a deep copy operation is performed, the cloned Person object, including its Person.IdInfo property, can be modified without affecting the original object.
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The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.