Access Modifiers and Default Access Modifiers in c#

             Access Modifiers and Default Access Modifiers in c#

 Default Access Modifiers: In C#, the default access modifier depends on the type:

• For classes and structs, the default is internal (if no access modifier is specified).
• For class members, the default is private.

In C#, access modifiers control the visibility and accessibility of types and members (such as classes, methods, fields, properties, etc.) in your code. They help define the scope and the level of access that other classes or assemblies have to these types and members. The access modifiers available in C# are:

1. public

• Description: The public access modifier makes the member or type accessible from anywhere, both within the same assembly and from other assemblies that reference it.
• Use Case: You typically use public when you want to expose a class or its members to the outside world, for example, in a library that other applications will use.

public class MyClass
{
    public int MyProperty { get; set; }
}

2. private

• Description: The private access modifier restricts access to the member or type to the containing class or struct only. It is the most restrictive access level.
• Use Case: You use private when you want to encapsulate data or behavior and prevent external access, ensuring that a class's internal workings are hidden from other classes.

public class MyClass
{
    private int myField;
    
    private void MyMethod() 
    {
        // Only accessible within MyClass
    }
}

3. protected

• Description: The protected access modifier makes the member accessible within its class and by derived (subclass) types, but not from other classes that are not in the inheritance hierarchy.
• Use Case: You use protected when you want to allow subclasses to access and modify a member, but prevent access from outside the class hierarchy.

public class BaseClass
{
    protected int protectedField;
}

public class DerivedClass : BaseClass
{
    public void AccessProtectedField()
    {
        protectedField = 10; // Valid because DerivedClass is a subclass of BaseClass
    }
}

4. internal

• Description: The internal access modifier makes the member or type accessible only within the same assembly (i.e., the same project or module). It is not accessible from other assemblies.
• Use Case: You use internal when you want to allow access within the same assembly but keep the member or type hidden from other assemblies, which is useful for implementation details that don't need to be exposed externally.

internal class MyClass
{
    internal void MyMethod() { }
}

5. protected internal

• Description: The protected internal access modifier is a combination of protected and internal. It makes the member accessible within its class, by derived classes, and within the same assembly.
• Use Case: Use protected internal when you want a member to be accessible within its own assembly, as well as by derived types, but still keep it hidden from non-derived classes outside of the assembly.

public class BaseClass
{
    protected internal int protectedInternalField;
}

6. private protected

• Description: The private protected access modifier is a combination of private and protected. It makes the member accessible only within the containing class and derived classes, but only if they are in the same assembly.
• Use Case: This modifier is useful when you want to restrict access to members to the class itself and its subclasses, but only within the same assembly, which helps in controlling the access more strictly than protected internal.

public class BaseClass
{
    private protected int privateProtectedField;
}

Summary of Access Modifiers:

Access Modifier	Access Scope	Usage Example
public	Accessible from anywhere (within the same assembly and outside).	API classes, public methods or properties
private	Accessible only within the containing class or struct.	Encapsulating internal data and methods
protected	Accessible within the containing class and derived classes.	To allow subclass access but not outside classes
internal	Accessible within the same assembly only.	For internal implementation details not exposed outside
protected internal	Accessible within the same assembly or from derived classes.	Combination of protected and internal
private protected	Accessible within the containing class and derived classes within the same assembly.	To allow access in the class and its subclasses but restrict access outside the assembly

Special Considerations:

• Default Access Modifiers: In C#, the default access modifier depends on the type:
  • For classes and structs, the default is internal (if no access modifier is specified).
  • For class members, the default is private.

Example Usage:

public class ExampleClass
{
    // Public member can be accessed anywhere
    public int publicValue;
    
    // Private member is accessible only within this class
    private int privateValue;
    
    // Protected member is accessible in this class and derived classes
    protected int protectedValue;
    
    // Internal member is accessible within the same assembly
    internal int internalValue;
    
    // Protected internal member is accessible within the same assembly and in derived classes
    protected internal int protectedInternalValue;
    
    // Private protected member is accessible within this class and derived classes in the same assembly
    private protected int privateProtectedValue;
}

In general, you should aim to encapsulate your class members by making them as restrictive as necessary (e.g., private or protected) and only expose them via properties, methods, or other public interfaces when needed.