Overwriting a ref parameter

RefParameter.cs

using System;

class Point
{
    public int X { get; set; }
    public int Y { get; set; }
}

class Program
{
    static void Main()
    {
        var p = new Point();
        X(ref p);
        Console.WriteLine($"{p.X}, {p.Y}"); // 10, 20
    }

    static void X(ref Point p)
    {
        p.X = 10;
        p.Y = 20;
    }
}