C＃4.0，可選參數和參數不能一起工作

Question

如何創建一個具有可選參數和參數的方法？

static void Main(string[] args) 
{ 

    TestOptional("A",C: "D", "E");//this will not build 
    TestOptional("A",C: "D"); //this does work , but i can only set 1 param 
    Console.ReadLine(); 
} 

public static void TestOptional(string A, int B = 0, params string[] C) 
{ 
    Console.WriteLine(A); 
    Console.WriteLine(B); 
    Console.WriteLine(C.Count()); 
} 

Answer 1

你唯一的選擇，現在是重載TestOptional（如你收到C＃4做）。不是首選，但它在使用點清理代碼。

public static void TestOptional(string A, params string[] C) 
{ 
    TestOptional(A, 0, C); 
} 

public static void TestOptional(string A, int B, params string[] C) 
{ 
    Console.WriteLine(A); 
    Console.WriteLine(B); 
    Console.WriteLine(C.Count()); 
} 

Answer 2

嘗試

TestOptional("A", C: new []{ "D", "E"}); 

Answer 3

這爲我工作：

static void Main(string[] args) { 

     TestOptional("A"); 
     TestOptional("A", 1); 
     TestOptional("A", 2, "C1", "C2", "C3"); 

     TestOptional("A", B:2); 
     TestOptional("A", C: new [] {"C1", "C2", "C3"}); 

     Console.ReadLine(); 
    } 

    public static void TestOptional(string A, int B = 0, params string[] C) { 
     Console.WriteLine("A: " + A); 
     Console.WriteLine("B: " + B); 
     Console.WriteLine("C: " + C.Length); 
     Console.WriteLine(); 
    }