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How does C# implement polymorphism?

Polymorphism manifests itself in C# in the form of multiple methods having the same name.

In some cases, multiple methods have the same name, but have different formal argument lists. These are overloaded methods.

In other cases, multiple methods have the same name, same return type, and same formal argument list. These are overridden methods.

This module concentrates on the use of method overloading to achieve compile-time polymorphism.

The class named Object

As you learned in an earlier module, every class in C# is a direct or indirect subclass of the class named Object . Methods defined in the Object class are inherited into all other classes. Some of those inherited methods may be overridden to make their behavior more appropriate for objects instantiated from the new subclasses. However, thismodule is not about overriding methods. Instead it is about overloading methods. I will cover method overriding in future modules.

Multiple methods with the same name

Overloaded methods have the same name and different formal argument lists. They may or may not have the same return type.

Polymorphism manifests itself in C# in the form of multiple methods having the same name. As mentioned above, this module concentrates on method overloading , sometimes referred to as compile-time polymorphism . Subsequent modules concentrate on method overriding , sometimes referred to as runtime polymorphism .

Compile-time and runtime polymorphism, what's the difference?

During the compilation and execution of polymorphic code, the compiler and the runtime system must decide which of two or more methods having the same namein the same scope must be executed. With method overloading, that decision is made when the program is compiled. With method overriding, that decision isdeferred and made at runtime. Hence we have the terms compile-time polymorphism and runtime polymorphism .

Every class extends some other class

Every class in C# (except for the class named Object ) extends some other class. If you don't explicitly specify the class that yournew class extends, it will automatically extend the class named Object .

A class hierarchy

Thus, all classes in C# exist in a class hierarchy where the class named Object forms the root of the hierarchy.

Some classes extend Object directly, while other classes are subclasses of Object further down the hierarchy (they extend classes that extend classes that extend Object ).

Methods in the Object class

You learned in an earlier module that the class named Object defines default versions of the following methods and that every class in thehierarchy inherits them:

  • Equals - Overloaded. Determines whether two Object instances are equal.
    • Equals(Object) - Determines whether the specified Object is equal to the current Object.
    • Equals(Object,Object) - Determines whether the specified Object instances are considered equal.
  • Finalize - Allows an Object to attempt to free resources and perform other cleanup operations before the Object isreclaimed by garbage collection.
  • GetHashCode - Serves as a hash function for a particular type.
  • GetType - Gets the Type of the current instance.
  • MemberwiseClone - Creates a shallow copy of the current Object.
  • ReferenceEquals - Determines whether the specified Object instances are the same instance.
  • ToString - Returns a String that represents the current Object.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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