Polymorphism

Object_Oriented_Programming/Polymorphism

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+--POLYMORPHISM--
+
+The term "Polymorphism" is the combination of "poly" + "morphs" which means 
+many forms. It is a greek word. In object-oriented programming, we use 3 main 
+concepts: inheritance, encapsulation, and polymorphism.
+
+Real Life Example Of Polymorphism :
+
+Let's consider a real-life example of polymorphism. A lady behaves like a teacher in a
+classroom, mother or daughter in a home and customer in a market. Here, a single person is
+behaving differently according to the situations
+
+There are two types of polymorphism --
+1. Compile-time polymorphism 
+2. Run-time polymorphism
+
+* Compile time polymorphism:
+
+The overloaded functions are invoked by matching the type and number of
+arguments. This information is available at the compile time and, therefore,
+compiler selects the appropriate function at the compile time. It is achieved
+by function overloading and operator overloading which is also known as
+static binding or early binding. 
+
+Now, let's consider the case where function name and prototype is same.
+
+ class A // base class declaration.
+ {
+ int a;
+ public:
+ void display()
+ {
+ cout<< "Class A ";
+ }
+ };
+class B : public A // derived class declaration.
+{
+ int b;
+ public:
+ void display()
+ {
+ cout<<"Class B";
+ }
+};
+
+In the above case, the prototype of display() function is the same in both the base and derived class. Therefore, 
+the static binding cannot be applied. It would be great if the appropriate function is selected at the run time. This 
+is known as run time polymorphism.
+
+*Run time polymorphism:
+
+Run time polymorphism is achieved when the object's method is invoked at the
+run time instead of compile time. It is achieved by method overriding which is also
+known as dynamic binding or late binding.
+
+C++ Runtime Polymorphism Example
+Let's see a simple example of run time polymorphism in C++.
+
+// an example without the virtual keyword.
+#include <iostream>
+using namespace std;
+class Animal {
+ public:
+void eat(){
+cout<<"Eating...";
+ }
+};
+class Dog: public Animal
+{
+ public:
+ void eat()
+ { cout<<"Eating bread...";
+ }
+};
+int main(void) {
+ Dog d = Dog();
+ d.eat();
+ return 0;
+}
+
+Output:
+Eating bread...
+
+Compile time polymorphism                                                                   Run time polymorphism
+The function to be invoked is known at the compile time.                           The function to be invoked is known at the run time.
+It is also known as overloading, early binding and static binding.                 It is also known as overriding, Dynamic binding and late binding.
+
+Overloading is a compile time polymorphism where more than                         Overriding is a run time polymorphism where more than one 
+one method is having the same name but with the different                          method is having the same name, number of parameters and 
+number of parameters or the type of the parameters.                                the type of the parameters.
+
+It is achieved by function overloading and operator                                It is achieved by virtual functions and pointers.
+overloading.
+
+It provides fast execution as it is known at the compile time.                     It provides slow execution as it is known at the run time.
+It is less flexible as mainly all the things execute at the compile                It is more flexible as all the things execute at the run time.
+time.
+