Preventing Access Public Member of Base Class From Derived Class in C#-CodePudding

Is this possible to preventing access public member (such as method, variable etc.) of base class from derived class instance? For example;

public class BaseClass
{
    public int m_a;
}

public class DerivedClass : BaseClass
{
    base.m_a = 10; //good
}

but, I don't want to this;

DerivedClass dc = new DerivedClass();
dc.m_a = 20; //not good

Is that possible?

CodePudding user response：

protected means the derived class can access it, however, the derived class can access the property of it's own instance also.

       static void Main(string[] args)
        {
            BaseClass bc = new BaseClass();
            DerivedClass dc = new DerivedClass();
           
           
            dc.doSomething(); //set value of baseClass from DerivedClass

            // dc.m_a = 20; //'Program.BaseClass.m_a' is inaccessible due to its protection level
            // bc.m_a = 20; //'Program.BaseClass.m_a' is inaccessible due to its protection level


            Console.WriteLine("Hello World!");
        }

       
        class BaseClass {
            protected int m_a;

            public void setValue(int m_a) {
                this.m_a = m_a;
            }
        }

        class DerivedClass : BaseClass {
            BaseClass baseClass = new BaseClass();
           
            public void doSomething() {
                this.m_a = 5;          // valid. You are accessing your own variable
                //baseClass.m_a = 5;   // invalid. You are attempting to access the protected property externally
                baseClass.setValue(5); // valid. Using a public setter
            }
        }

CodePudding user response：

Unfortunately, the base class is a .net class. Because of this, I can not use any modifier for base class.

CodePudding user response：

try this

public static void Main()
{
DerivedClass dc = new DerivedClass();
dc.m_a = 20; // ERROR!

}


public class BaseClass
{
    protected int m_a;
}

public class DerivedClass : BaseClass
{
    public DerivedClass()
    {
        m_a=20; //No Error
    }
}