Access Modifier in C#

Modifier in Java
Override of access modifiers
private access modifier
private constructor
protected access modifier
internal access modifier
protected internal access modifier
public access modifier
Access modifier and inheritance

1. Modifier in Java

The access modifiers in CSharp specifies accessibility (scope) of a data member, method, constructor or class.

There are 5 types of access modifiers in CSharp:

private
protected
internal
protected internal
public

2. Override of access modifiers

Modifier	Description
private	Access is limited to within the class definition. This is the default access modifier type if none is formally specified
protected	Access is limited to within the class definition and any class that inherits from the class
internal	Access is limited exclusively to classes defined within the current project assembly
protected internal	Access is limited to the current assembly and types derived from the containing class. All members in current project and all members in derived class can access the variables.
public	There are no restrictions on accessing public members.

The table below illustrates give you an overview of how to use the access modifiers.

	Same Assembly			Different Assembly
	Access Modifier	Access within class	Access within package	Access outside package by subclass only	Access outside package and not in subclass.
private	Y
protected	Y	Y		Y
internal	Y	Y	Y
protected internal	Y	Y	Y
public	Y	Y	Y	Y	Y

You can see more details follow the example below:

3. private access modifier

The private access modifier is accessible only within class.

You cannot access to private member outside the class that defines that member. CSharp will notify error at the compile time of the class.

4. private constructor

Constructor, method, field are known as members of the class.

If you create a class and have a private constructor, you cannot create a object of this class from that private constructor, outside this class. Let's see an illustrative example:

5. protected access modifier

protected access modifier: Access is limited to within the class definition and any class that inherits from the class.

The protected access modifier can be applied on the data member, method and constructor. It can't be applied on the class, interface...

6. internal access modifier

Access is limited exclusively to classes defined within the current project assembly

An assembly is the compiled output of your code, typically a DLL, but your EXE is also an assembly. It's the smallest unit of deployment for any .NET project.

The assembly typically contains .NET code in MSIL (Microsoft Intermediate language) that will be compiled to native code ("JITted" - compiled by the Just-In-Time compiler) the first time it is executed on a given machine. That compiled code will also be stored in the assembly and reused on subsequent calls.

7. protected internal access modifier

protected internal access modifier is a combination of protected and internal access modifier, the member of the class with this access modifier, you can only access to this member in the class that defines it or subclasses and included in the same Assembly.

8. public access modifier

The public access modifier is accessible everywhere. It has the widest scope among all other modifiers.

9. Access modifier and inheritance

In CSharp, you can override amethod of superclass with a method of the same name and parameters, and return type in the subclass, but you are not allowed to change its access level.

However, you can create a method with the same name, parameters, return type, but different access levels if using the new keyword, the fact that this is a different method unrelated to the method of the parent class.

The difference between the overrideandnew has been explained in the document "Inheritance and polymorphism in CSharp" you can look at:

CSharp Inheritance, Polymorphism