What is Interface in C#.net
Interface is a type which contains only the signatures/declaration of methods/functions, delegates or events.
Declaration /signature of methods meaning method having no implementation as follows,
void Display(string name); //By Default interface member is Public
It does not contain implementation of methods. Implementation of the methods is done by the class that which implements the interface.
Interface is a contract that defines the signature of the functionality. So if a class is implementing
a interface it says to the outer world, that it provides specific behavior.
Example: If a class is implementing ‘Idisposable’ interface that means it has a functionality to release unmanaged resources. Now external objects using this class know that it has contract by which it can dispose Un-used unmanaged objects.
Important points to remember about Interface:
a) Supports multiple interface (Single Class can implement multiple interfaces.)
b) If a class implements an interface, then it has to provide implementation to all its methods.
c) Contains declaration / signature of methods only, it does not contain implantation of methods.
d) It cannot contain Data members eg.:
string name
e) By Default interface members are Public (We cannot set any access modifier to interface members).
f) Interface cannot contain constructors.
Example: – Defining an Interface,
interface IDisplay
{
string name(string name); //By Default interface members are Public
int a ; // Error, It cannot contain Data members .
}
class Demo : IDisplay
{
public string name(string name) //Must be declare Public
{
return “” + name;
}
}