C# Language Polymorphism Types of Polymorphism
Example
Polymorphism means that a operation can also be applied to values of some other types.
There are multiple types of Polymorphism:
- Ad hoc polymorphism:
containsfunction overloading. The target is that a Method can be used with different types without the need of being generic. - Parametric polymorphism:
is the use of generic types. See Generics - Subtyping:
has the target inherit of a class to generalize a similar functionality
Ad hoc polymorphism
The target of Ad hoc polymorphism is to create a method, that can be called by different datatypes without a need of type-conversion in the function call or generics. The following method(s) sumInt(par1, par2) can be called with different datatypes and has for each combination of types a own implementation:
public static int sumInt( int a, int b)
{
return a + b;
}
public static int sumInt( string a, string b)
{
int _a, _b;
if(!Int32.TryParse(a, out _a))
_a = 0;
if(!Int32.TryParse(b, out _b))
_b = 0;
return _a + _b;
}
public static int sumInt(string a, int b)
{
int _a;
if(!Int32.TryParse(a, out _a))
_a = 0;
return _a + b;
}
public static int sumInt(int a, string b)
{
return sumInt(b,a);
}
Here's a example call:
public static void Main()
{
Console.WriteLine(sumInt( 1 , 2 )); // 3
Console.WriteLine(sumInt("3","4")); // 7
Console.WriteLine(sumInt("5", 6 )); // 11
Console.WriteLine(sumInt( 7 ,"8")); // 15
}
Subtyping
Subtyping is the use of inherit from a base class to generalize a similar behavior:
public interface Car{
void refuel();
}
public class NormalCar : Car
{
public void refuel()
{
Console.WriteLine("Refueling with petrol");
}
}
public class ElectricCar : Car
{
public void refuel()
{
Console.WriteLine("Charging battery");
}
}
Both classes NormalCar and ElectricCar now have a method to refuel, but their own implementation. Here's a Example:
public static void Main()
{
List<Car> cars = new List<Car>(){
new NormalCar(),
new ElectricCar()
};
cars.ForEach(x => x.refuel());
}
The output will be was following:
Refueling with petrol
Charging battery
