从另一个构造函数调用构造函数

public class Animal
{
    public string Name { get; set; }

    public Animal() : this("Dog")
    {
    }

    public Animal(string name)
    {
        Name = name;
    }
}

var dog = new Animal();      // dog.Name will be set to "Dog" by default.
var cat = new Animal("Cat"); // cat.Name is "Cat", the empty constructor is not called.