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copied!<p>If your <code>Student</code> type is a class (reference type), a list will only contain references to those instances. This means that when you make a copy of your list, the copied list will also have only references that still point to the same <code>Student</code> instances. By copying your list you simply duplicated your references but not the instances. What you have after the copy is something like this:</p> <pre><code>List 1 List 2 instance S1 ref to S1 ref to S1 Name: Akash ref to S2 ref to S2 ... ... ... </code></pre> <p>So if you do something like <code>list1[0].Name = "Jim"</code>, you'll update the instance <code>S1</code> and you'll see the change in both lists, since both lists refer to the same set of instances.</p> <p>What you need to do is create a clone of not only the list in this case but all the objects <em>inside</em> the list - you need to clone all your <code>Student</code> objects as well. This is called a deep copy. Something like this:</p> <pre><code>class StudentList : List<Student>, ICloneable { public object Clone () { StudentList oNewList = new StudentList (); for ( int i = 0; i < Count; i++ ) { oNewList.Add ( this[i].Clone () as Student ); } return ( oNewList ); } } </code></pre> <p>You call this like so:</p> <pre><code>StudentList oClonedList = lstStudent.Clone () as StudentList; </code></pre> <p>You also need to make your <code>Student</code> class cloneable by implementing the <a href="http://msdn.microsoft.com/en-us/library/system.icloneable.aspx" rel="nofollow"><code>ICloneable</code></a> interface.</p> <p>Don't forget, though, that after this, you'll have 2 separate lists with 2 independent sets of <code>Student</code> objects - modifying one <code>Student</code>instance will have no effect on students in your other list.</p>

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