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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

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
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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