How to find the index of an element of a one-dimensional array with a full name by last name?

Question

Arrays

Hello.
The essence of the task - there is an array with the full name of the employees:
let's say string [] array = { "Ivanov Ivan Ivanovich", "Sidorov Sidor Sidorovich", "Petrov Petr Petrovich",};
you need to do a search by last name, so that when you enter from the keyboard: Ivanov, it returns the full name.

As I understand it, you need to check all elements for similarity and, having received the index of a similar one, display it on the screen.
The problem is in finding a similar one, I tried Array.Indexof () - it doesn’t work, it searches only for the full name.

P.S. according to the condition of the problem, we have 1 array with full name, cannot be split into 3 with separate last name, first name and patronymic.

Answer 1

string[] array = { "Иванов Иван Иванович", "Сидоров Сидор Сидорович", "Петров Петр Петрович" };
            var find = "сид";
            var finded = array.Where(v => v.Split(' ')[0].ToLower().Contains(find)).ToList();//[0] Сидоров Сидор Сидорович

PS If you need not a partial, but a complete match, then change Contains to Equals