Indexing in Linq

Question

Why do we use index in "where clause"? Is it an auto generated number ans starts from zero? Simple example would be really helpful.

var query =... Where((p,index)..)

Answer 1

The index should refer to the index of the current item in the collection (the zero based iteration).

There is a simple example on this page.

Answer 2

Yes, it is an auto-generated number that starts from zero.

Use it whenever you need access to the index in your query.

var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

var evenLetters = alphabet.Where((p, index) => (index % 2) == 1);
var oddLetters = alphabet.Where((p, index) => (index % 2) == 0);

Answer 3

var oddElements = query.Where((p, index) => index % 2 == 1);