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==Access Control - demonstrate the various forms of access control==

<source lang="csharp">using System;
public class Class1 : Class2 {
public static void Main(string[] strings) {
Class1 class1 = new Class1();
Class2 class2 = new Class2();
Class3 class3 = new Class3();
class2.A_public();
class1.B_protected();
class1.C_private();
class3.D_internal();
class1.E_internalprotected();
class3.E_internalprotected();
}
public void C_private() {
Console.WriteLine("Class1.C_private");
}
}
internal class Class3 {
public void A_public() {
Console.WriteLine("Class3.A_public");
}
protected void B_protected() {
Console.WriteLine("Class3.B_protected");
}
internal void D_internal() {
Console.WriteLine("Class3.D_internal");
}
public void E_internalprotected() {
Console.WriteLine("Class3.E_internalprotected");
}
}

public class Class2 {
public void A_public() {
Console.WriteLine("Class2.A_public");
}
protected void B_protected() {
Console.WriteLine("Class2.B_protected");
}
private void C_private() {
Console.WriteLine("Class2.C_private");
}
internal void D_internal() {
Console.WriteLine("Class2.D_internal");
}
internal protected void E_internalprotected() {
Console.WriteLine("Class2.E_internalprotected");
}
}</source>

==C#"s Access Specifiers==

<p>An access specifier determines how other parts of a program can access a class member.</p>
<p>Member access is controled by four access specifiers:</p>
<OL><LI>public,</LI><LI>private,</LI><LI>protected,</LI><LI>internal.</LI></OL>
<OL><LI>public member can be accessed by any other code in your program.</LI><LI>Main() is declared as public because it will be called by code outside of its class (the operating system).</LI><LI>private member can be accessed only by other members of its class.</LI><LI>A protected member is public within a class hierarchy, but private outside that hierarchy.</LI><LI>A protected member is created by using the protected access modifier.</LI><LI>The internal modifier declares that a member is known throughout all files in an assembly, but unknown outside that assembly.</LI><LI>The protected internal access level can be given only to class members.</LI><LI>A member declared with protected internal access is accessible within its own assembly or to derived types.</LI></OL>
7.15.Access Modifier
7.15.1.
C#"s Access Specifiers
7.15.2.
<A href="/Tutorial/CSharp/0140__Class/Theuseofvariousaccessmodifiers.htm">The use of various access modifiers</a>
7.15.3.
<A href="/Tutorial/CSharp/0140__Class/AccessControldemonstratethevariousformsofaccesscontrol.htm">Access Control - demonstrate the various forms of access control</a>
7.15.4.
<A href="/Tutorial/CSharp/0140__Class/Visibilitymodifiersindicatewhichothercodeitemscanviewanitem.htm">Visibility modifiers indicate which other code items can view an item.</a>

==The use of various access modifiers==

<source lang="csharp">class MyClass
{
public string publicStringField;
protected internal string protectedInternalStringField;
internal string internalStringField;
protected int protectedField = 150;
private int privateField;
public void setPrivateField(int privateField)
{
this.privateField = privateField;
}
public int getPrivateField()
{
return privateField;
}
public void Start()
{
System.Console.WriteLine("Starting MyClass ...");
privateMethod();
System.Console.WriteLine("MyClass started");
}
private void privateMethod()
{
System.Console.WriteLine("Turning starter motor ...");
}
}

class MainClass
{
public static void Main()
{
MyClass myMyClass = new MyClass();
myMyClass.publicStringField = "Toyota";
myMyClass.protectedInternalStringField = "MR2";
myMyClass.internalStringField = "black";
myMyClass.setPrivateField(1995);
System.Console.WriteLine("myMyClass.publicStringField = " + myMyClass.publicStringField);
System.Console.WriteLine("myMyClass.protectedInternalStringField = " + myMyClass.protectedInternalStringField);
System.Console.WriteLine("myMyClass.internalStringField = " + myMyClass.internalStringField);
System.Console.WriteLine("myMyClass.getPrivateField() = " + myMyClass.getPrivateField());
myMyClass.Start();
}
}</source>
<pre class=codeResult>myMyClass.publicStringField = Toyota
myMyClass.protectedInternalStringField = MR2
myMyClass.internalStringField = black
myMyClass.getPrivateField() = 1995
Starting MyClass ...
Turning starter motor ...
MyClass started</pre>

==Visibility modifiers indicate which other code items can view an item.==

<source lang="csharp">Modifier Applies To Description
public Any types or members visible to any other code.
protected Any member of a type, also any nested type visible only to any derived type.
internal Any member of a type, also any nested type visible only within its containing assembly.
private Any types or members visible only inside the type to which it belongs.
protected internal Any member of a type, also any nested type visible to any code within its containing assembly and also to any code inside a derived type.</source>

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