Copying a list of lists of int's in c#

Questions & Answers
1

Hello, I’m having a bit of trouble with lists, mainly I want to copy contents of one list to another one without leaving any connection between them. But for some reason I’m not able to do that, I’ve noticed that this happens only with lists of lists. Thanks for any help

 List<int> A = new List<int> ();
	List < List<int>>B= new List < List<int>>();
	List < List<int>>D= new List < List<int>>();

	void Start () {
		A.Add (3);
		A.Add (4);
		A.Add (5);
		B.Add (new List<int> (A));
		D = new List<List<int>> (B); //why new doesn't mean new?
		B [0] [1] = 7;
		print (D [0] [1]); //prints 7 and I want 4
	}
}
2

//why new doesn’t mean new?

I believe the answer to this has to do with references. List B contains REFERENCES to its elements (just one element at this point, namely list A). So when you ask for a new List B, it will make you a brand new list (because you ask for it), but the content of the list will be copied, i.e. the references are copied but still reference the same elements. This is why changing the element in D will also change the element in B.

Anyhow, I guess THIS explains it better!