Deferred Query Execution: shows how query execution is deferred until the query is enumerated at a foreach statement. : Deferred Query « LINQ « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. LINQ
3. Deferred Query

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass {
    public static void Main() {
        int[] numbers = new int[] { 5, 4, 1, 3, 9 };

        int i = 0;
        var q =
            from n in numbers
            select ++i;
        foreach (var v in q) {
            Console.WriteLine("v = {0}, i = {1}", v, i);
        }
    }
}