An interface
looks like a class, but has no implementation. The only thing it contains is
definitions of events, indexers, methods and/or properties.
The reason interfaces only
provide definitions is because they are inherited by classes and structs,
which must provide an implementation for each interface member defined.
Example
//defining first interface
interface Ifirst
{
void
sum(int a, int
b);
}
//defining
second interface which inherits first interface
interface Isecond:Ifirst
{
void
sub(int a, int
b);
}
//defining
class which inherits second interface
class newClass : Isecond
{
//implementing
interface defined methods
public void sum(int a, int b)
{
MessageBox.Show("Sum is: " + (a + b).ToString());
}
public void sub(int a, int b)
{
MessageBox.Show("Difference is: " + (a - b).ToString());
}
}
Demonstrating use
//creating instance of class
newClass c = new newClass();
private void btnSum_Click(object
sender, EventArgs e)
{
//calling
sum() of Ifirst interface
c.sum(Convert.ToInt32(txtNum1.Text),
Convert.ToInt32(txtNum2.Text));
}
private
void btnSub_Click(object
sender, EventArgs e)
{
//calling
sub() of Isecond interface
c.sub(Convert.ToInt32(txtNum1.Text),
Convert.ToInt32(txtNum2.Text));
}
