访问修饰符

public

同一程序集中的任何其他代码或引用该程序集的其他程序集都可以访问该类型或成员。

The type or member can be accessed by any other code in the same assembly or another assembly that references it.

private

只有同一类或结构中的代码可以访问该类型或成员。

The type or member can be accessed only by code in the same class or struct.

protected

只有同一类或结构或者此类的派生类中的代码才可以访问的类型或成员。

The type or member can be accessed only by code in the same class or struct, or in a class that is derived from that class.

internal

同一程序集中的任何代码都可以访问该类型或成员，但其他程序集中的代码不可以。

The type or member can be accessed by any code in the same assembly, but not from another assembly.

protected internal

由其声明的程序集或另一个程序集派生的类中任何代码都可访问的类型或成员。 从另一个程序集进行访问必须在类声明中发生，该类声明派生自其中声明受保护的内部元素的类，并且必须通过派生的类类型的实例发生。

The type or member can be accessed by any code in the assembly in which it is declared, or from within a derived class in another assembly. Access from another assembly must take place within a class declaration that derives from the class in which the protected internal element is declared, and it must take place through an instance of the derived class type.

1. protected的权限和private的权限很相似，唯一不同的是protected类或成员可以被子类继承，而private类型成员不可以被继承。
2. 类的默认修饰符符是internal.成员的默认修饰符是private.