无法访问派生类中的变量 [英] Cannot access variable in derived class

问题描述

我无法在派生类中访问i. m.i不起作用.为什么?

I am not able to access i in my derived class. m.i is not working. Why?

 public class MyClass
    {
        protected int i;
        public MyClass()
        {

        }

        public virtual void Display()
        {
            Console.WriteLine("Base dis");
        }
    }

    public class MyCla : MyClass
    {
        public MyCla()
        {


        }
        int ij = 12;
        public new void Display()
        {
            MyClass m = new MyClass();
            // m.i is inaccessible here
            Console.WriteLine("Derived dis");
        }
    }

推荐答案

这是因为protected变量和属性仅可用于派生类，在派生上下文中(因此通过使用this引用)和当前类的实例(因此，如果m是MyCla则可以使用).

That is because protected variables and properties are only available to derived classes, within the derived context (thus by referencing it with this), and to instances of the current class (so if m was MyCla it would have worked).

MyCla m = new MyCla();
int x = m.i;

一个选项是使字段internal或protected internal(如果需要)，从而使其对于程序集中的所有类均可用.

An option is to make the field internal, or protected internal if you wish, which makes it available to all classes within the assembly.

这是一个编译示例.

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