constructor is a special member function in c++ because its name is the same as classname.

it should be declared in the public section.

Constructors do not have a return type, not even void.

Constructor is called automatically when an object of the class is created.

it is used to initialize the data member of a class.

it may have a default argument.

constructor in cpp

The syntax to Define Constructor Inside the Class is :

classname (argument_list)

The syntax to Define Constructor Outside the Class is :

classname :: classname(argument_list)

Types of Constructors in C++ :

  1. Default Constructor
  2. Parameterized Constructor
  3. Copy Constructor
  4. Dynamic Constructor

Also read this :- operator overloading in c++.

1. Default Constructor in c++

A Constructor which contains no parameter is called Default Constructor.

The syntax to Define the Default Constructors in c++ is : 

class classname
 {
     public :
            
         classname()  // This Constructor is Default Constructor
 }

Here’s an example of a Default Constructors declaration in c++

#include<iostream>
using namespace std;
class item
{
   int no;
   int price;
   public :
   item() // item is a name of Constructor
   {
      cout<<"Enter the No & Price : n";
      cin>>no>>price;
   }
   void putdata()
   {
      cout<<"No = "<<no<<endl;
      cout<<"Price = "<<price;
   }
};
int  main()
{
   item x1;
   x1.putdata();
   return 0;
}

output

Enter the No & Price : 2 43 No = 2 Price = 43

2. Parameterized Constructor in c++

A Constructor which contains an Argument is called Parameterized Constructor.

The syntax to Define Parameterized Constructors in c++ is :

class classname
{
   public :
   classname(list_of_arguments) // This Constructor is Parameterized Constructor
}

3. Copy Constructor in c++

A Constructor which contains a Reference of the Object same Class as an Argument then it is called Copy Constructor.

The syntax to Define Copy Constructor is :

class classname
{
   public :         
   classname(classname con) // This Constructor is Copy Constructor
}

4. Dynamic Constructors in c++

it is used to Allocate Memory at the time of Creating an Object

Here’s an example of a Dynamic Constructors declaration in c++

classs classname
{
   public:
   classname(char *variable) // This Constructor is Dynamic Constructor
   {
      //code
   }
}