Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All
Important This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here.

protected (C# Reference)

The protected keyword is a member access modifier. A protected member is accessible within its class and by derived classes. For a comparison of protected with the other access modifiers, see Accessibility Levels.

A protected member of a base class is accessible in a derived class only if the access takes place through the derived class type. For example, consider the following code segment:

// protected_keyword.cs
using System;
class A
    protected int x = 123;

class B : A
    static void Main()
        A a = new A();
        B b = new B();

        // Error CS1540, because x can only be accessed by
        // classes derived from A.
        // a.x = 10; 
        // OK, because this class derives from A.
        b.x = 10;   

The statement a.x =10 generates an error because A is not derived from B.

Struct members cannot be protected because the struct cannot be inherited.

In this example, the class DerivedPoint is derived from Point; therefore, you can access the protected members of the base class directly from the derived class.

// protected_keyword_2.cs
using System;
class Point 
    protected int x; 
    protected int y;

class DerivedPoint: Point 
    static void Main() 
        DerivedPoint dpoint = new DerivedPoint();

        // Direct access to protected members:
        dpoint.x = 10;
        dpoint.y = 15;
        Console.WriteLine("x = {0}, y = {1}", dpoint.x, dpoint.y); 


x = 10, y = 15

If you change the access levels of x and y to private, the compiler will issue the error messages:

'Point.y' is inaccessible due to its protection level.

'Point.x' is inaccessible due to its protection level.

For more information, see the following sections in the C# Language Specification:

  • 3.5.1 Declared Accessibility

  • 3.5.3 Protected access for instance members

  • 3.5.4 Accessibility constraints

  • 10.2.3 Access Modifiers

Community Additions

© 2015 Microsoft