How to identify whether the objects are just referenced or just copied? .net Memory Management

Question

Hello

I'm confused to find whether an object is either copied or the reference of the object is held while equating it to some other objects.

Examples

int i =5;
int j = i;

Reference or copy of data?

DataSet ds = dsOtherDataSet.Copy();

Reference or copy of data?

DataView dvTemp = dsTestDataSet.Copy().DefaultView;

What happens here?

Regards

NLV

Answer 1

if type is struct then copy is always done by value. if class then by reference.

What is done inside methods like Copy, Clone etc. is not strictly defined and is up to the one who implements them.

In case of DataSet.Copy msdn tells us that deep copy is done ("Copies both the structure and data for this DataSet."), meaning that it completely recreates dataset. Still, Copy method returns reference to new dataset.

Answer 2

int i = 5;
int j = i;

Copy of data as int is a value type and is stored on the stack.

DataSet ds = dsOtherDataSet.Copy();

According to the documentation the Copy method copies both the structure and data of the DataSet. So ds will have the same structure as the original but if there are reference values stored inside both will point to the same memory location.

DataView dvTemp = dsTestDataSet.Copy().DefaultView;

Only the reference is copied as DataView is a reference type.

Answer 3

In the first case the int's aren't objects they are value types. So for "int j = i" another int is created and then the value from i is copied into it. If you use Copy then it probably creates another copy of the object using deep copy. But you should find out wheter the copy is a deep-copy or just a shallow copy. If you would use DataSet ds = dsOtherDataSet, or Object obj = someOtherObject then only their adress is passed, so it is by reference only.