C#高級功能（三）Action、Func，Tuple

Action和Func泛型委托實際上就是一個.NET Framework預定義的委托，3.5引入的特性。基本涵蓋了所有常用的委托，所以一般不用用戶重新聲明。

Action系列泛型委托，是沒有返回參數的委托，最多可以有16參數，也可以沒有參數；Func系列的委托是有返回值的委托，最多可以有16個參數；

元組是C# 4.0引入的一個新特性，編寫的時候需要基於.NET Framework 4.0或者更高版本。元組使用泛型來簡化一個類的定義.

提供用於創造元組對象的靜態方法。最多可以提供創建新的 8 元組，即八元組。

Action

public delegate void Action()

//void method(); 
Action test1 = () => { Console.WriteLine("void method();"); };
//void method(x);
Action<int> test2 = (x) => { Console.WriteLine("void method(t1)"); };
//void method(x, y);
Action<int, int> test3 = (x, y) => { Console.WriteLine("void method(t1, t2)"); };

public delegate void Action<in T1, in T2, in T3, in T4, in T5, in T6, in T7, in T8, in T9,
 in T10, in T11, in T12, in T13, in T14, in T15, in T16>()

Func

public delegate TResult Func<out TResult>()

//int method();
Func<int> test4 = () => 10;
//int method(x);
Func<int, int> test5 = (x) => x * 2;
//int method(x,x);
Func<int, int, int> test6 = (x, y) => x * y;

public delegate TResult Func<in T1, in T2, in T3, in T4, in T5, in T6, in T7, in T8, in T9, in T10,
 in T11, in T12, in T13, in T14, in T15, in T16, out TResult>()

Tuple

public static Tuple<T1> Create<T1>(
    T1 item1
)
var tuple1 = Tuple.Create(1);
Console.WriteLine(tuple1.Item1);     // Displays 1

var tuple1 = new Tuple<int>(1);
Console.WriteLine(tuple1.Item1);     // Displays 1

Tuple.Create<T1, T2, T3, T4, T5, T6, T7, T8> 方法 (T1, T2, T3, T4, T5, T6, T7, T8)

var primes = new Tuple<int, int, int, int, int, int, int, 
                 Tuple<int>>(1, 2, 3, 4, 5, 6, 7,   new Tuple<int>(8));//元祖裡面可以嵌套元祖

Tuple<int, int, int, int, int, int, int, Tuple<int, int, int>> test = 

new Tuple<int, int, int, int, int, int, int, Tuple<int, int, int>>(1, 2, 3, 4, 5, 6, 7, new Tuple<int, int, int>(8, 9));

//元祖准確的可以說是當做擁有多個返回值的一種方法，不用使用ref，out了，比較方便。