Acess Specifiers(Access Modifiers) in C#

Access Specifiers or Access Modifiers in C#

What is an access specifier?

Access Modifiers are used to define scope of types as well as their members i.e who can access them and who can not.

C# supports five access specifiers

• Private
• Protected
• Internal
• Protected Internal
• Public

Note: Members defined in a type with any scope or specifier are always accessible with in the type(Same Class), restrictions comes into picture only when they try to access them outside of the type.

 Private Access Specifier in C#:

Members declared as private under a class or structure can not be accessed outside of type in which they are defined and  moreover their default scope is private only.Types can't declared as private(classes,structures), so private is applicable to members only(variables,methods,functions).

Note:Interface can not contain any private members and default scope for interface members is public. See in Diagram format

Example For Private Access Modifier:

class Private_Type { private int X1; private string X2; public string Y2; public int Y1; public Private_Type() { // Accessing private members with in same type X1 = 10; X2 = "Private value"; Y1 = 20; Y2 = "Public value"; } } class Test { static void main() { Private_Type ObjPrivateType = new Private_Type(); Console.WriteLine("Public Variables are " + ObjPrivateType.Y2 + " , " + ObjPrivateType.Y1); //Accessing other class private members will return error Inaccessible due to its protection level Console.WriteLine("Public Variables are " + ObjPrivateType.X2 + " , " + ObjPrivateType.X1);// this line returns error as we can not access them } }

  Protected Access Specifier in C#:

Members declared as protected under a class can be accessed only with in the class or a child class, non - child class can not consume them. Types can't be declared as protected also, so this is applicable to only members. See in Diagram format

Example for Protected Access Specifier:

class Protected_Types { protected int X1; public int Y1; protected void AccessProtected() { Console.WriteLine("Accessing Protected Method"); } } class ChildProtectedTypes : Protected_Types { protected int Z1; public void Sum() { X1 = 10;// accessing protected members in child class Y1 = 20;// accessing public members in child class Z1 = 30;// accessing protected types in same type Console.WriteLine(X1 + Y1 + Z1); AccessProtected(); // accessing protected method in child class } } class TestChildProtectedTypes { static void main() { ChildProtectedTypes ObjChildProtectedTypes = new ChildProtectedTypes(); ObjChildProtectedTypes.Sum();//we can access public members only using object ObjChildProtectedTypes.Y1 = 40;//we can access public members only using object } }

In the ProtectedTypes class we declared two variables Protected x1 and public y1. In the childprotectedtype class both variables were consumed. In the childprotectedtype class we declare another protected variable z1. see in Sum() method we accessed all of the variables either protected or public. protected members can access only in children class. we can not access them using object of the class. In TestChildProtectedTypes class i can access only Y1 we can't access any protected variables, You see public variable can be accessed by anywhere.   

Internal Access Specifier in C#:

Members and types that are declared as Internal can be accessed only within the project both from child or non - child classes. The default scope for any type in c# is Internal only. These members can be accessed by using inheritance and by creating object of the class or type. This can be accessed only with in the project outside of the project it can't be accessed. See in Diagram format

Protected Internal Access Specifier in C#:

Members declared as protected internal will have dual scope. i.e with in the project they behave as internal providing access to any where in the project, outside the project they will change to protected and still provide access to their child classes. Types(Class and Structures) can not be declared as protected internal also.  See in Diagram format

   Example for Protected Internal access specifier

namespace OopsProject { class Protected_Internal { protected string P1; protected internal string pi; public string Pu; private string pri; internal string Inter; void Hello() { Console.WriteLine("this is Hello method in Protected Internal class"); } public void PublicMethod() { Console.WriteLine("this is PublicMethod in Protected Internal class"); } private void PrivateMethod() { Console.WriteLine("This is PrivateMethod in Protected Internal class"); } protected internal void ProtectedInternalMethod() { Console.WriteLine("This protected internal method in Protected internal class"); } protected void ProtectedMethod() { Console.WriteLine("This Protected Method in Protected internal class"); } internal void InternalMethod() { Console.WriteLine("This is InternalMethod in Protectedinternal class"); } } class ChildProtectedInternal : Protected_Internal { // Accessing members in child class void AccessParentMembers() { P1="accessing Protected Member in child class";// No error pi = "accessing protected internal member in child class"; //No error Pu = "Accessing Public members in child class";// No error pri = "Accessing private members in child class";// error "In accessible due to its protection level" Inter = "Accessing internal members in child class";// No Error ProtectedInternalMethod();// No error in accessing Protected internal method in child class ProtectedMethod();// No error in accessing Protected method in child class PublicMethod();// No error in accessing public method in child class InternalMethod();// No error in accessing Protected internal method in child class PrivateMethod();// Error In accessible due to its protection level } } class TestProtectedInternal { static void main() { Protected_Internal ObjProtecteInternal = new Protected_Internal(); ObjProtecteInternal.P1 = "accessing Protected Member in non - child class";// Error In accessible due to its protection level ObjProtecteInternal.pi = "accessing protected internal member in non -child class"; //No error ObjProtecteInternal.Pu = "Accessing Public members in non -child class";// No error ObjProtecteInternal.pri = "Accessing private members in non -child class";// error "In accessible due to its protection level" ObjProtecteInternal.Inter = "Accessing internal members in non -child class";// No Error ObjProtecteInternal.ProtectedInternalMethod();// No error in accessing Protected internal method in non- child class ObjProtecteInternal.ProtectedMethod();// Error In accessible due to its protection level ObjProtecteInternal.PublicMethod();// No error in accessing public method in non- child class ObjProtecteInternal.InternalMethod();// No error in accessing Protected internal method in non-child class ObjProtecteInternal.PrivateMethod();// Error In accessible due to its protection level } } }

In the above example I created a class Protected_Internal where i declared all types of members and i accessed all of these members using inheritance and in non- child class.

Public Access Specifier in C#:

A type or a member of a type if declared as public is global in scope which can be accessed from any where. See in Diagram format

 an example public access specifier

namespace OopsProject { class Public_Type { public int Var1; public string var2; public void Show() { Console.WriteLine("show method in Public_type class"); } public void display() { Console.WriteLine("display method in Public_type class"); } } class childpublictype:Public_Type { void AccessParentMembers() { // we can all the public members of public type class in child class Var1 = 10; var2 = "second"; Show(); display(); } } class NonChildClass { static void Main() { Public_Type ObjPublicType = new Public_Type(); // we can all the public members of public type class in non-child class ObjPublicType.Var1 = 10; ObjPublicType.var2 = "second"; ObjPublicType.Show(); ObjPublicType.display(); } } }

See in the above example we can access all the public members of publictype class in child class and nonchildclass.

Conclusion:

I hope you got some information regarding access specifiers in C# through this example. You can find diagramatic format of Access Specifiers explaination here

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