C# 4.0, optional parameters and params do not work together

问题

How can i create a method that has optional parameters and params together?

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());
}

回答1:

Your only option right now is to overload the TestOptional (as you had to do before C# 4). Not preferred, but it cleans up the code at the point of usage.

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());
}

回答2:

Try

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

回答3:

This worked for me:

    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();
    }

来源：https://stackoverflow.com/questions/3948971/c-sharp-4-0-optional-parameters-and-params-do-not-work-together

标签

.net

c#-4.0

params

optional-parameters