Polymorphism in C++ - PDF.co (2023)

Polymorphism means a name with many forms, in C++ polymorphism is a mechanism where the same function, name and operator can be used to work with different input parameters. Polymorphism is one of the most important features of object-oriented programming. A real world example would be a single person who has multiple roles such as father, brother, husband, friend, etc.

Polymorphism in C++ - PDF.co (1)

UsThere are two types of polymorphism in C++

  • Compile-time polymorphism
  • runtime polymorphism

The following diagram can give a clear overview of polymorphism and its types:

Polymorphism in C++ - PDF.co (2)

(Video) Buckys C++ Programming Tutorials - 55 - Introduction to Polymorphism

Polymorphism at compile time

C++ provides compile-time polymorphism in operators and functions called operator overloading and function overloading respectively, compile-time polymorphism is also called early binding or static binding, let's explore both.

1.1 Functional Overload

Function overloading is a polymorphism mechanism where the same function name can be called with different parameters; the parameters must differ in number or with different data types. Let's see an example:

#include<bits/stdc++.h>usando espacio de nombres std;int add(int numero1, int numero2){ return (numero1 + numero2);}float add(double numero1, double numero2){ return (numero1 + numero2); }void principal(){ cout<<añadir(5,10); cout<<adicionar(5.1,10.2);}

We can see in the example above that there are two functions with the same name as add, the first with two integer parameters and the second with two double parameters. Compiling this program in a C compiler will generate an error saying Function declaration with the same name, but in C++ this code will compile and when run add(5,10) will call the function with integer definition and add (5.1,10.2) calls add with double definition. The compiler distinguishes functions based on the mechanism calledname mutilation.

Name change:Renaming adds additional information to functions of the same name, this additional information is mainly based on function parameters, each compiler can use its own renaming technique, there is no hard and fast rule about renaming. For the example above, the C++ compiler could change the names internally and the object's code could look like this:

int add_int(int number1,int number2);float add_double(duplo number1,duplo number2);void main() cout<<add_int(5,10); cout<<add_double(5.1,10.2);}

Let's look at some examples of function overloading

example 1

#include<bits/stdc++.h> using the default namespace;int add(int number1, int number2,int number3){ return (number1 + number2 + number3);}int add(int number1, int number2){ return ( Number1 + Number 2);}

The above example has different number of parameters for both functions, now the compiler calls the functions based on the number of parameters passed, the first function calls with 3 arguments and the second with 2 arguments calling the respective functions.

(Video) Polymorphism in Object Oriented Programming | C++ Placement Course Lecture 21.4

example 2

usando el espacio de nombres std;int add(int number1, int number2){ return (number1 + number2);}float add(int number1, int number2){ return (number1 + number2);}void main(){ cout< <add( 5,10); cout<<adicionar(5,10);}

For the example above, the compiler throws a compilation error stating that the function call is ambiguous because both functions have the same number of parameters with the same type, although the return type is different, the function overloading mechanism does not distinguish between function calls based on return types.

Example 3

#include<bits/stdc++.h>using std namespace;int add(int number1, int number2,int number3 = 5){ return (number1 + number2 + number3);}int add(int number1, int number2){ return ( Zahl1 + Zahl2);}void main(){ cout<<add(5,10,15); cout<<add(5,10);}

For the code above, the C++ compiler issues an ambiguous declaration of a compile-error function, even though the first add function has three parameters, the last one is a default parameter, so the compiler cannot decide which function to call. The first function can also be called by passing two arguments and the second function can also be called by passing two arguments, this creates ambiguity and the compiler will throw an error during compilation.

Rules for overloading functions

  • The names of the functions must be the same.
  • The number of parameters passed to the function must be different, excluding default parameters, or parameters passed to functions must be of different data types (if the same parameter numbers are passed).
  • Data types such as char, unsigned char, short are promoted to int and float are promoted to double.
  • Functions that differ only in the return type do not support function overloading.

1.2 Operator Overload

Operator overloading is a mechanism in C++ that allows the use of an operator in a custom class. For example, we can overload the "+" operator within a class to add the content of two objects and return it to the third object.

#include<bits/stdc++.h> using the std;class namespaceComplex{ private: int real; imaginary integer; public: Complex(int ​​r, int i) { real = r; imaginary = I; } complex operator + (complex &obj){ complex result; real.result = real + real.obj; imaginary.result = imaginary + imaginary.obj; return result; } void print(){ cout<< real << "imaginary" << imaginary << endl; }}void main() { Complex c1(10,15),C2(20,25); complex c3 = c1+c2; C3.print();}Output: 30 40 imaginary

As you can see we have the functionComplex operator + (Complex &obj)This is an operator-overloaded function that is automatically called when adding two objects of the Complex class, e.g. B. c3 = c1 + c2;

The syntax of the operator overload function is as follows

(Video) 5. C++ Language: Polymorphism in C++ PDF Notes available in description

<return type> operator <current operator> (parameter)

The above example shows the "+" operator used to overload operators in the same way we can overload other operators like - , *, /, <, >, = etc., but there are few operators , which cannot be overloaded like


Size of()



(Video) CppCon 2017: Louis Dionne “Runtime Polymorphism: Back to the Basics”

Rules for operator overloading

  • C++ compatible operators can only be overloaded.
  • Operator priority remains the same.
  • There must be at least one user-defined data type, we cannot just use built-in data types.
  • Overloaded operators cannot include default parameters, except for the function call operator "()"
  • The assignment "=", the subscript "[]", the function call "()", and the arrow operator "->" These operators must be defined as member functions, not as friend functions.
  • Some operators like the assignment "=", the address "&" and the comma ""," are overloaded by default.
  • The meaning of the overloaded operator should not be changed.

2.0 runtime polymorphism

C++ provides run-time polymorphism, which can be achieved through function substitution; Run-time polymorphism is also known as late binding or dynamic binding. We say a function overrides when a derived class has the same name as the function within the base class, so we call the base class function override. Let's see an example:

#include<bits/stdc++.h> using the std;class namespaceIntelligent{ public: virtual void show(){ cout<<”paint::show()”<< endl;} void draw(){ cout<<”paint::draw()”<< endl; }}KlasseKreis: public Paint { public: void show(){cout<<”circle::show()”<< endl; } void dibujar(){ cout<<”circle::draw()”<< endl; }} void main () { Malen * basePtr; Círculo derivadoObj; basePtr = &objderivado; basePtr->mostrar(); basePtr->desenhar(); vuelve 0;}Result:circle::show() paint::draw()

As we can see, basePtr->show() calls show function of derived class, since show() function is realized as virtual function in base class, virtual functions are called based on class object which is pointer of assigned is the base class, while non-virtualA function like draw() from the base class is called.

virtual function

AvirtualFunction is a function in a base class that is declared using the keywordvirtualwhich tells the compiler to use dynamic or late link mechanisms instead of static or early link mechanisms, using virtual functions we can achieve run-time polymorphism, the class that declares functions as virtual, the compiler you need to create onevirtual tableto set up the dynamic call

pure virtual function

C++ provides a pure virtual function mechanism where the virtual function in the base class is just the placeholder and doesn't implement anything, but derived classes must implement it, pure virtual functions are declared as

virtual blank() = 0

They are assigned 0; A class with all purely virtual functions is called an abstract base class

(Video) John Bandela “Polymorphism != Virtual: Easy, Flexible Runtime Polymorphism Without Inheritance”

Let's wrap up the topic with the pros and cons of polymorphism.


  • Reduces the burden on the programmer of remembering the different function names for the different parameters to be called; the programmer simply calls the same function with the necessary parameters.
  • Polymorphism can be applied to classes and user-defined data types that define user-defined operations on user-defined data types.
  • Dynamic linking helps reduce code and increase reuse.
  • Polymorphism supports data abstraction.


  • Polymorphism is considered difficult for developers to implement.
  • Run-time polymorphism increases execution time.
  • Run-time polymorphism is hard to understand, less readable
  • With operator overloading, the developer can change the meaning of the operator, because when "+" is overloaded, it can perform other addition operations that the compiler recognizes as errors, this way the basic meaning of the operators can be changed.
  • Runtime polymorphism requires the compiler to maintain a virtual table for dynamic linking, which equates to additional memory.
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What is polymorphism in C++ explain in detail? ›

Polymorphism means "many forms", and it occurs when we have many classes that are related to each other by inheritance. Like we specified in the previous chapter; Inheritance lets us inherit attributes and methods from another class. Polymorphism uses those methods to perform different tasks.

What is a real life example of polymorphism in C++? ›

A real-life example of polymorphism is a person who at the same time can have different characteristics. A man at the same time is a father, a husband, and an employee. So the same person exhibits different behavior in different situations.

What is polymorphism and its example? ›

A person at the same time can have different characteristics. Like a man at the same time is a father, a husband, an employee. So the same person possesses different behavior in different situations. This is called polymorphism.

What type of polymorphism do C++ offer? ›

C++ supports two types of polymorphism: Compile-time polymorphism, and. Runtime polymorphism.

What is the best way to define polymorphism? ›

What is polymorphism?
  1. Polymorphism is a feature of object-oriented programming languages that allows a specific routine to use variables of different types at different times.
  2. Polymorphism in programming gives a program the ability to redefine methods for derived classes.

What is the main function of polymorphism? ›

A function that can evaluate to or be applied to values of different types is known as a polymorphic function. A data type that can appear to be of a generalized type (e.g. a list with elements of arbitrary type) is designated polymorphic data type like the generalized type from which such specializations are made.

Why is polymorphism useful C++? ›

Polymorphism is one of the main features of object-oriented programming. Polymorphism in C++ allows us to reuse code by creating one function that's usable for multiple uses. We can also make operators polymorphic and use them to add not only numbers but also combine strings.

What is the best example for polymorphism? ›

The best example of polymorphism is human behavior. One person can have different behavior. For example, a person acts as an employee in the office, a customer in the shopping mall, a passenger in bus/train, a student in school, and a son at home.

What is the best example of a common polymorphism in humans? ›

Blood Groups. All the types of blood groups are examples of genetic polymorphism, such as the ABO blood group system. We see this system having more than two morphs: A, B, AB, and O are the variants present in the entire human population, but these groups vary in proportion in different parts of the world.

What are the 4 types of polymorphism? ›

Types of Polymorphism
  • Subtype polymorphism (Runtime) Subtype polymorphism is the most common kind of polymorphism. ...
  • Parametric polymorphism (Overloading) ...
  • Ad hoc polymorphism (Compile-time) ...
  • Coercion polymorphism (Casting)
Oct 23, 2020

What are the two 2 types of polymorphism? ›

There are two types of polymorphism which are the compile-time polymorphism (overload) and run-time polymorphism (overriding).

What are different methods of implementing polymorphism in C++? ›

We can implement polymorphism in C++ using the following ways:
  • Function overloading.
  • Operator overloading.
  • Function overriding.
  • Virtual functions.

What is the most common polymorphism? ›

Single nucleotide polymorphisms, frequently called SNPs (pronounced “snips”), are the most common type of genetic variation among people.

What are the advantages of polymorphism? ›

Advantages of Polymorphism
  • Programmers code can be reused via Polymorphism.
  • Supports a single variable name for multiple data types.
  • Reduces coupling between different functionalities.
4 days ago

What is polymorphism for dummies? ›

Polymorphism is the ability of an object to take on many forms. Any Java object that can pass more than one IS-A test is considered to be polymorphic— tutorialspoint. This means any child class object can take any form of a class in its parent hierarchy and of course itself as well.

What are the three types of polymorphism? ›

In Object-Oriented programming languages there are three types of polymorphism: subtype polymorphism, parametric polymorphism, and ad-hoc polymorphism.

What is polymorphism in oops? ›

Polymorphism is the ability of any data to be processed in more than one form. The word itself indicates the meaning as poly means many and morphism means types. Polymorphism is one of the most important concepts of object-oriented programming languages.

What is runtime polymorphism in C++? ›

In runtime polymorphism, the compiler resolves the object at run time and then it decides which function call should be associated with that object. It is also known as dynamic or late binding polymorphism. This type of polymorphism is executed through virtual functions and function overriding.

Can polymorphism be harmful? ›

Polymorphisms can have a harmful effect, a good effect, or no effect. Some polymorphisms have been shown to increase the risk of certain types of cancer.

What is application of polymorphism? ›

Application of Polymorphism

Polymorphism is very useful in the pharmaceutical field for the development of a drug. The structure of the solid crystal is important to determine the effectiveness of the drug and the effects it can have on the body.

Why does polymorphism occur? ›

According to the theory of evolution, polymorphism results from evolutionary processes, as does any aspect of a species. It is heritable and is modified by natural selection.

What are the four pillars of polymorphism? ›

These four pillars are Inheritance, Polymorphism, Encapsulation and Abstraction.

What is static vs runtime polymorphism? ›

Static polymorphism is polymorphism that occurs at compile time, and dynamic polymorphism is polymorphism that occurs at runtime (during application execution). An aspect of static polymorphism is early binding. In early binding, the specific method to call is resolved at compile time.

What is the difference between static polymorphism and dynamic polymorphism in C++? ›

Dynamic polymorphism happens at run time and static polymorphism at compile time. Dynamic polymorphism requires typically a pointer indirection at run time (read the post "Demystifying virtual functions, Vtable, and VPTR in C++"), but static polymorphism has no performance costs at run time.

Is overloading a type of polymorphism? ›

Overloading is of type static polymorphism.. overriding comes under dynamic (or run-time) polymorphism..

How many types of polymorphism are there *? ›

There are two types of polymorphism in Java: compile-time polymorphism and runtime polymorphism.

What are the two types of methods polymorphism can perform? ›

There are two main types of polymorphism i.e. runtime polymorphism and compile-time polymorphism. Runtime polymorphism is achieved through method overriding, and compile-time polymorphism is achieved through method overloading.

What are the three main techniques for modeling polymorphism in a database? ›

In relational modeling, there are three techniques that have been widely shared for covering this kind of problem. Here they are "single table inheritance", "class table inheritance", and "shared primary key".

What is polymorphism explain with the real time application? ›

Polymorphism is the ability of an object to take on different forms. In Java, polymorphism refers to the ability of a class to provide different implementations of a method, depending on the type of object that is passed to the method.

What is object in C++ with real life example? ›

C++ Classes/Objects

C++ is an object-oriented programming language. Everything in C++ is associated with classes and objects, along with its attributes and methods. For example: in real life, a car is an object. The car has attributes, such as weight and color, and methods, such as drive and brake.

What are the real world examples of multiple inheritance in C++? ›

C++ Multiple Inheritance

In C++ programming, a class can be derived from more than one parent. For example, A class Bat is derived from base classes Mammal and WingedAnimal . It makes sense because bat is a mammal as well as a winged animal.

What is the concept behind polymorphism? ›

Polymorphism is one of the core concepts of object-oriented programming (OOP) and describes situations in which something occurs in several different forms. In computer science, it describes the concept that you can access objects of different types through the same interface.

What is an example of polymorphism in OOP? ›

An excellent example of Polymorphism in Object-oriented programing is a cursor behavior. A cursor may take different forms like an arrow, a line, cross, or other shapes depending on the behavior of the user or the program mode.

What is the difference between static and dynamic polymorphism in C++? ›

Static polymorphism is polymorphism that occurs at compile time, and dynamic polymorphism is polymorphism that occurs at runtime (during application execution). An aspect of static polymorphism is early binding. In early binding, the specific method to call is resolved at compile time.

What are the 5 types of inheritance in C++? ›

Explore 5 Types of Inheritance in C++ With Examples
  • Single Inheritance.
  • Multiple Inheritance.
  • Multilevel Inheritance.
  • Hierarchical Inheritance.
  • Hybrid Inheritance.
5 days ago

Why do we need encapsulation in C++? ›

The main advantage of using Encapsulation is to hide the data from other methods. By making the data private, these data are only used within the class, but these data are not accessible outside the class.

Why is encapsulation used? ›

Encapsulation is used to hide the values or state of a structured data object inside a class, preventing unauthorized parties' direct access to them.

How do you enable polymorphism in C++? ›

We can implement polymorphism in C++ using the following ways:
  1. Function overloading.
  2. Operator overloading.
  3. Function overriding.
  4. Virtual functions.

What are the two methods used to implement polymorphism? ›

There are two main types of polymorphism i.e. runtime polymorphism and compile-time polymorphism. Runtime polymorphism is achieved through method overriding, and compile-time polymorphism is achieved through method overloading.

Is polymorphism possible in C++? ›

Polymorphism in C++

Typically, polymorphism occurs when there is a hierarchy of classes and they are related by inheritance. C++ polymorphism means that a call to a member function will cause a different function to be executed depending on the type of object that invokes the function.

What is the difference between hierarchical and multiple inheritance? ›

The type of inheritance where many subclasses inherit from one single class is known as Hierarchical Inheritance. Hierarchical Inheritance a combination of more than one type of inheritance. It is different from the multilevel inheritance, as the multiple classes are being derived from one superclass.

What is real life example of encapsulation? ›

Consider the below real time example: Encapsulation: As a driver you know how to start the car by pressing the start button and internal details of the starting operations are hidden from you. So the entire starting process is hidden from you otherwise we can tell starting operation is encapsulated from you.

What is a diamond problem in C++? ›

The diamond problem The diamond problem occurs when two superclasses of a class have a common base class. For example, in the following diagram, the TA class gets two copies of all attributes of Person class, this causes ambiguities.


1. Polymorphism in C++ | Function and Operator Overloading | Virtual Function in C++ Hindi #17
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2. C++Now 2018: Louis Dionne “Runtime Polymorphism: Back to the Basics”
3. CppCon 2014: Jason Lucas "Polymorphism with Unions"
4. C++ Weekly - Ep 248 - Understand the C++17 PMR Standard Allocators and Track All the Things
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5. CppCon 2018: Mateusz Pusz “Effective replacement of dynamic polymorphism with std::variant”
6. CppCon 2017: Viktor Kirilov “DynaMix: A New Take on Polymorphism in C++”


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