Breve introduzione a C# 4 ed alle sue feature più importanti/interessanti.

6. classAbc{ public intA(); } Abco =newAbc(); intn = o.A(); o.Foo();

7. intnumber = 42; number = 1.0; intnumber = 42; number = (int)1.0;

8. intnumber = 42; number = “123”; intnumber = 42; number = int.Parse(“123”);

9. 42 + 8.0 + “123”;

10. int[] array = newint[5]; int elemento = array[100]; A oggetto = (A)newB();

11. dynamic o = newA(); o.Foo();

12. var text = “pippo”; varnumber = random.Next(); varresult = 24.0 * 2;

13. unsafe{ int*p = newint[100]; p[100] = 0; //boom }

15. “sono una stringa” string ciao = “ciao”.Trim();

16. public classMyClass { int_myNumber; public intYourNumber; }

17. public classMyClass { int_myNumber; public voidSetNumber(int v){ if(v == 0) thrownewException(); _myNumber = v; } }

18. MyClassc = newMyClass(); c.SetNumber(100);

19. public classMyClass { int_myNumber; public intNumber { get { return_myNumber; } } }

20. public classMyClass { int_myNumber; public intNumber { get { return_myNumber; } set { _myNumber = value; } } }

21. MyClassc = newMyClass(); c.Number = 100; intnumber = c.Number;

22. public classMyClass { public event EventHandlerNumberChanged; public intNumber { set { _myNumber = value; NumberChanged(this, null); } }

23. MyClassc = newMyClass(); c.NumberChanged += EventHandler(Gestore); c.Number = 100; private voidGestore(objectsender, EventArgsargs){ Console.WriteLine(“Numero cambiato.”); }

24. public classSystem.Object { public virtualobjectEquals(objectobj); public virtualintGetHashCode(); publicTypeGetType(); public virtualstringToString(); }

25. public classMyClass { File_myFile; publicMyClass(){ _myFile = newFile(…); } publicMyClass(stringname){ _myFile = File.Open(name); } }

26. MyClass c1 = newMyClass(); MyClass c2 = newMyClass(“nome”);

27. public classMyClass { File_myFile; //... ~MyClass(){ _myFile.Close(); } }

28. public classContenitore { int_number; public overridestringToString(){ return “Numero: ” + _number; } }

29. public classBase { public virtualintA(){ return42; } public stringB(){ return “don’t panic”; } } public classDeriv { public overrideintA(){ return100; } }

30. public interface IFoo{ int Bar(); stringBaz(intarg); }

31. public abstractclassFoo{ public abstractint Bar(); public virtualstringBaz(intarg){ return “baz”; } }

32. IDisposable public classMyClass : IDisposable { File_myFile; ~MyClass(){ _myFile.Close(); } public voidDispose(){ _myFile.Close(); GC.SuppressFinalize(this); } }

33. using(var file = newMyFile()){ // ... } // oggetto distrutto

34. delegate stringFiltro(string s); FiltrofiltraSpazi = delegate(string s){ returns.Replace(“ ”, “”); } filtraSpazi(“ciao mondo”); // “ciaomondo”

35. delegate stringFiltro(string s); FiltrofiltraSpazi = s => s.Replace(“ ”, “”);

36. ThreadPool.QueueUserWorkItem(o => { // operazione lunga }, null);

37. public staticclassStringExtensions { public staticstringGreet(thisstring s){ return“Ciao ” + s + “!”; } }

39. DateTime

40. public staticstringToIso8601(thisDateTimeval) { returnval.ToString(@"yyyy-MM-ddHH:mm:ss.ff", CultureInfo.InvariantCulture); }

42. newMyClass(“ciao”, 10); newMyClass<int>(100);

43. public classWidgetContainer { object[] _array; public voidAdd(Widgetinstance){ ... } public WidgetGet(intindex){ return (Widget)_array[index]; } } public classContainer<T> { T[] _array; public voidAdd(Tinstance){ ... } public TGet(intindex){ return_array[index]; } } //Container<Widget>

44. Attribute public MyAttribute : Attribute { public intCount { get; set; } } [My(Count = 10)] publicMyClass { }

45. varc = newMyClass(); varattrs = c.GetType() .GetCustomAttributes(typeof(MyAttribute), true); varattr = (MyAttribute)attrs[0]; Console.WriteLine(attr.Count);

47. IEnumerable<T> IEnumerator<T> { T Current { get; } boolMoveNext(); void Reset(); } IEnumerable<T> { IEnumerator<T> GetEnumerator(); }

48. IEnumerable<T> int[] fibo = new { 0, 1, 1, 2, 3, 5, 8 }; foreach(var i infibo){ Console.Write(i); } // stampa: 0112358

49. IList<T> IList<int> fibo = new { 0, 1, 1, 2, 3 }; fibo[2] = 2; //0, 1, 2, 2, 3 int c = fibo.Count; // c = 5

50. System.Collections.Generic List<T> : IList<T> Dictionary<K,T> : IDictionary<K,T> LinkedList<T> : ICollection<T> Stack<T> : IEnumerable<T>

51. System System.Collections System.Diagnostics System.Globalization System.IO System.Net System.Reflection System.Runtime System.Security System.Text System.Threading

52. System.Linq (System.Core.dll)

53. varnums = from n inEnumerable.Range(0, 100) letsquare = n * n wheresquare >= 49 select n; // 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ...