How exactly keyword 'params' work?

Question

The following code sample prints:

T
T[]
T[]

While first two lines are as expected, why compiler selected param array for a regular array?

public class A
{
    public void Print<T>(T t)
    {
        Console.WriteLine("T");
    }

    public void Print<T>(params T[] t)
    {
        Console.WriteLine("T[]");
    }
}

class Program
{
    static void Main(string[] args)
    {
        A a = new A();
        a.Print("string");
        a.Print("string","string");
        a.Print(new string[] {"a","b"});
    }
}

Answer 1

Under the hood

a.Print("string","string");

is just syntactic sugar for

a.Print(new string[]{"string","string"});

EDIT: Like I said, the params keyword only automagically creates the array for you, you tell the compiler: either accept an array of T directly or use the X input params to construct that array.

Answer 2

It addition to what others have said, the params keyword also causes a ParamArrayAttribute to the generated for array parameter. So, this...

public void Print<T>(params T[] t) { }

Is generated by the compiler as...

public void Print<T>([ParamArray] T[] t); { }

It is that attribute which indicates to the compiler and the IDE that the method can be called using simpler syntax...

a.Print("string", "string");

rather than...

a.Print(new string[] { "string", "string" });