In c# interface Why access modifier is not use

Nikhil Ladva

9y1.1k.NET

In c# Interface Why access modifier is not use ?

5 Replies

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Milan Prajapati9y ago
All the interface methods are Public. You can't create an access modifier in interface. If you want to use one, use Abstract class.
Kanniyappan Krish9y ago
Interface members are always public because the purpose of an interface is to enable other types to access a class or struct. No access modifiers can be applied to interface members
sudipta sanyal9y ago
Actually, Interface is a half made class, we just declare the method names and we need to implement the method in derived class, if we need to implement the method on derived class then it should be accessed in the derived class, for this we did not define the access modifier
Nitin Sontakke9y ago
Let me try to give a bit more detailed explanation.

The answer to your question lies in the answer to the question "Why do we need the interfaces at all?".

Here is a scenario for which you might take interface approach. You want to persist all the business objects (such as Customer, Invoice, Order, etc.) in the database. Which means they should all have methods such as .Save(), .Delete(), etc. So you declare an interface.

public interface IPersist
{
void Save()
void Delete()
}
You then implement the Interface for each class. In OO languages it is acceptable to have parameter data types of interface name. So you imagine you write a method as follows:

public void SaveObject(IPersist objectToSave)
{
objectToSave.Save() // objectToSave will have only those properties and methods which are declare as part of IPersist interface.
}

The above code will allow to call interface methods and properties only if they are declare public in that class otherwise they cannot be called, which defeats the purpose of declaring interface.

That's why every member declared in interface must be public.

Hope you understand.
Ranjit Powar9y ago
All interface members are public by default.