Question

Under remarks, it says

If the type of source implements IList, that implementation is used to obtain the element at the specified index. Otherwise, this method obtains the specified element.

String does not implement IList<T>. Does that mean this will be an O(n) operation if I declare something like,

IEnumerable<char> myString = "stringy";

?

Answer 1

ElementAt when applied to a type which is a string will be an O(N) operation. It does not implement IList<char> and hence ElementAt won’t do any optimizations on it and instead enumerates through the IEnumerable<char> until it reaches the specified index.