C# Programming.

The C# language: its type system, its members, its patterns and the rules the compiler enforces. Covers 16 topics.

• C# Programming · 1 of 3

  Pattern matching

  In C# pattern matching, what do the and and or combinators allow?

  Atwo input values tested togetherBtwo switch arms sharing a single bodyCtwo types merged into one unionDtwo patterns combined in one arm

• C# Programming · 2 of 3

  Extension methods

  In C#, which output line of this program shows the iterator body had not run when Doubled() was called?

  using System;using System.Collections.Generic;using System.Linq;static class Help{    public static IEnumerable<int> Doubled(this IEnumerable<int> xs)    {        Console.WriteLine("walking");        foreach (int x in xs) yield return x * 2;    }}class P{    static void Main()    {        var q = new[] { 1, 2, 3 }.Doubled();        Console.WriteLine("built");        Console.WriteLine(string.Join(",", q));        Console.WriteLine(q.Count());    }}

  AThe third line, 2,4,6BThe first line, builtCThe first line, walkingDThe fifth line, 3

• C# Programming · 3 of 3

  Lambdas

  In C#, what does a closure created by a lambda that uses outer locals hold?

  AA copy of the whole enclosing stack frameBOnly the parameters that it declaresCReferences to the captured variablesDSnapshots of the values at creation time