The subclass constructor will call the parent class without the parameter constructor by default

1. Calling the parent class without a parameter constructor is the default!

The constructor method of a subclass accesses the parameterless construction method of the parent class by default: There is a row of default statement base () after the constructor method in the child class

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classFu {   publicFu()     {         Console.WriteLine("fu");     } } classZi : Fu {     publicZi()         : base()//不管是否显式调用，控制台都会输出fu     {         Console.WriteLine("zi");     } } Zi z = newZi();

The constructor of the parent class is executed before the parent class is initialized and the subclass is initialized.

2. How do I access the parameter constructor of a parent class?

You can access the parameter constructors in the parent class through super (parameters). Can pass this (parameter ...) To access other constructors in this class.

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classFu {      publicFu(inta)     {         Console.WriteLine("fu"+a);     } } classZi : Fu {      publicZi():base(0)//调用父类有参构造函数     {         Console.WriteLine("zi");     }     publicZi(inta):base(a)     {         Console.WriteLine("zi"+a);     } }

If a constructor is defined, the class does not have a default parameterless constructor, and if there is no default in the parent class, the subclass constructor must display the constructor that invokes the parent class

The subclass constructor will call the parent class without the parameter constructor by default