c# - Optional argument followed by Params

Question

So I see that it's possible to have a method signature where the first parameter provides a default value and the second parameter is a params collection.

What I can't see is a way to actually use the default value of the first argument.

Is it at all possible?

Example method:

void WaitAllTasks(string message = "Running Task.WaitAll", params Task[] tasks);

I initially tried omitting the message parameter when calling the method and also tried using named parameters, which doesn't work with params.

It compiles, but is it possible to use it?

Answer 1

我可以找到三种调用方法的方法，而无需为第一个参数指定值：

using System;

class Test
{
    static void PrintValues(string title = "Default",
                            params int[] values)
    {
        Console.WriteLine("{0}: {1}", title, 
                          string.Join(", ", values));
    }

    static void Main()
    {
        // Explicitly specify the argument name and build the array
        PrintValues(values: new int[] { 10, 20 });
        // Explicitly specify the argument name and provide a single value
        PrintValues(values: 10);
        // No arguments: default the title, empty array
        PrintValues();
    }
}

我还没有找到一种在不显式构建数组的情况下指定多个值的方法......