How to call an interface in C#

Question

interface ISample
{
    int fncAdd();
}

class ibaseclass
{
    public int intF = 0, intS = 0;
    int Add()
    {
        return intF + intS;
    }
}
class iChild : ibaseclass, ISample
{
    int fncAdd()
    {
        int intTot = 0;
        ibaseclass obj = new ibaseclass();
        intTot = obj.intF;
        return intTot;
    }
}

I want to call ISample in static void Main(string[] args) but I dont know how to do that. Could you please tell me how?

Solution 1

An interface cannot be instantiated by itself. You can't just call an interface. You need to instantiate a class that actually implements the interface.

Interfaces don't and can't do anything by themselves.

For example:

ISample instance = new iChild(); // iChild implements ISample
instance.fncAdd();

The following questions provide more detailed answers about this:

• Why is an interface or an abstract class useful? (or for what?)
• Interface vs Abstract Class (general OO)

Solution 2

You can't "call" interface or create instance of it.

What you can do is have your class implement the interface then use its method fncAdd.

Solution 3

Do you mean?:

static void Main(string[] args)
{
    ISample child = new iChild();
    child.fncAdd();
}

Although, as stated by others the code doesn't seem like it's using inheritance correctly.