LINQ query in lambda syntax

Question

What would be the proper way to write this query with lambda syntax?

var palindromes = from i in Enumerable.Range(100, 9900)
 from j in Enumerable.Range(100, 9900)
 let product = (i * j)
 where product.ToString() == new string(product.ToString().Reverse().ToArray())
 orderby product
 select product;

Answer 1

var palindromes = Enumerable.Range(100, 9900)
 .SelectMany(
 i => Enumerable.Range(100, 9900),
 (i, j) => i * j)
 .Where(p => /* where condition */)
 .OrderBy(p => p);

That's not exactly how compiler will transform your query, but result should be the same.

You can check rules compiler follows when transforming syntax query to method invokaction in c# specification.