"Parameterless Struct Constructor"

public readonly struct User {
	public readonly string Name;
	public readonly int Age;

	public User() { // Struct constructor defined with no parameters!
		Name = "<no name>";
		Age = -1;
	}
}

// ...

var u = new User();
Console.WriteLine(u.Name + " " + u.Age); // Prints "<no name> -1"


Code snippet taken from "Complete C# Quick Reference - C# 10".