Is polymorphism another term for overloading?

Question

Is polymorphism another term for overloading?

Answer 1

No, it is not.

Overloading refers to creating a method or an operator with the same name, but different parameters and - depending on the language - different return types.

Overriding refers to reimplementing a method with the same signature in a derived class and enables polymorphism - the decision what implementation of an overwritten method to call is made at runtime depending on the actual type of the object.

class BaseClass
{
     public void DoStuff(Int32 value) { } // Overloading

     public void DoStuff(String value) { } // Overloading

     public virtual void DoOtherStuff(String value) { }
}

class DerivedClass : BaseClass
{
    public override void DoOtherStuff(String value) { } // Overriding
}

Usage example

BaseClass instance = null;

if (condition)
{
    instance = new BaseClass();
}
else
{
    instance = new DerivedClass();
}

// Using overloads
instance.DoStuff(4);
instance.DoStuff("four");

// Polymorphism - it depends on the actual type of the object
// referenced by the variable 'instance' if BaseClass.DoOtherStuff()
// or DerivedClass.DoOtherStuff() will be called at runtime.
instance.DoOtherStuff("other stuff");