C＃错误：家长不包含一个构造函数的参数0

问题描述：

我的code是

public class Parent
{

    public Parent(int i)
    {
        Console.WriteLine("parent");
    }
}

public class Child : Parent
{
    public Child(int i)
    {
        Console.WriteLine("child");
    }

}

我收到错误：

家长不包含一个构造函数0参数。

Parent does not contain a constructor that takes 0 arguments.

我了解的问题是，父与0参数没有构造函数。但我的问题是，为什么我们需要零参数的构造函数？为什么不是没有它的code的工作？

I understand the problem is that Parent has no constructor with 0 arguments. But my question is, why do we need a constructor with zero arguments? Why doesn't the code work without it?

答

既然你不明确地调用父类的构造为您的孩子类的构造函数的一部分，还有就是插入一个无参数父类的构造隐式调用。该构造函数不存在，所以你会得到错误。

Since you don't explicitly invoke a parent constructor as part of your child class constructor, there is an implicit call to a parameterless parent constructor inserted. That constructor does not exist, and so you get that error.

要纠正这种情况，你需要添加的显式调用：

To correct the situation, you need to add an explicit call:

public Child(int i) : base(i)
{
    Console.WriteLine("child");
}

或者，你可以添加一个无参数的父类的构造：

Or, you can just add a parameterless parent constructor:

protected Parent() { }

C＃错误：家长不包含一个构造函数的参数0

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