将列表转换为参数C＃

Question

I have this following list:

var myList = new List<KeyValuePair<string, object>>();

And this function:

public void Test(params KeyValuePair<string, object>[] list)

How can I do a conversion of the list to params when using the function? Like that:

Test(myList);

Answer 1

您方法声明KeyValuePair<string, object>[] list声明它将接受一个数组，因此您需要将列表转换为数组，如下所示

Test(myList.ToArray());

Answer 2

You should convert the list to form which is accepted as parameter. In this case convert List to Array

Hence,

var arrayParam = mylist.ToArray();
Test(arrayParam);

Answer 3

Given the original question, I think it's worth clarifying how the params keyword functions. It has to be a decorator on a 1D array, and simply allows an alternate syntax for calling the function.

For example if we have a string concatenation function:

public string Test(string[] names) {
    return String.Join(",", names);
}

This can be called using

Test(new[] { "Fred", "Wilma", "Pebbles"});

but the inclusion of the params keyword simply allows a friendlier looking calling syntax:

public string Test(params string[] names) {
    return String.Join(",", names);
}

Test("Fred", "Wilma", "Pebbles");

I'm not a huge fan of the params keyword, but I do sometimes use it to make calling code more readable (as in this example).

So when the OP asks " How can I do a conversion of the list to params? ", the underlying truth is that you don't, as params is not a type and is simply a "syntactical sugar" feature to give an alternative syntax for passing in an array.