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When I change a value in one list of collection , another list that is a copy of first list, also changed


msdn.microsoft.com/en-us/library/21k0e39c%28v=vs.110%29.aspx

The elements of s2 still point to the same underlying objects (it is a shallow copy).

I.e. s2 contains references to the same block object instances as the elements 0, 1 and 2 of s1

To make complete copies of your object depends on what your Block class is/does. You may find http://msdn.microsoft.com/en-us/library/t63sy5hs.aspx basic overview of the difference between a value type and a reference type useful.

If the Block class has only value type fields then a memberwise clone http://msdn.microsoft.com/en-us/library/system.object.memberwiseclone%28v=vs.110%29.aspx is sufficient (this link also explains the key differences between a shallow and deep copy).

If it contains reference fields (e.g. references to other objects) you should add a .Copy or .Clone method. Essentially, such a method would create a new instance of its class, assigning its values to the new class value fields (or first doing a memberwise clone) and dealing with the reference types (how depends on what they are).

You should start a new question explaining your Block object and best practices for making copies of instances of it.


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