Collection constructor with collection initialzer

You can pass anything that is a valid constructor parameter. For example, List permits construction from any enumerable, so you can do this:

	string[] ab = new string[] { "a", "b" };
	List<string> abcd = new List<string>(ab) { "c", "d" };
	// abcd has four elements: "a" "b" "c" and "d"
	// Resulting list is { 1, 2, 3, 4, 5 }
	var list2 = new List<int>(list) { 4, 5 };
	// Resulting list is { 4, 2, 3 }
	var list3 = new List<int>(list) { [0] = 4 };
	string[] ab = new string[] { "a", "b" };
	List<string> abcd = new List<string>(ab) { "c", "d" };
	// abcd has four elements: "a" "b" "c" and "d"

view raw collectionInit.cs hosted with ❤ by GitHub

this combination notation is useful if you want to clone an existing collection and then make some tweaks to it.