CONSTRUCTOR IN C++

Constructor In C++

• Constructor is a 'special' member function.
• Class name and function name are same.
• Constructor cannot be virtual.
• An object with a constructor cannot be used as a member of a union.
• It is automatically called when objects is created for the class.

Types Of Constructor

• Default constructor- no argument. Ex:book()
• Parameterized constructor – takes argument Ex: book(10, c++)
• Copy constructor- takes objects as argument Ex: book(book &obj)

Advantage

1.  Using a constructor Objects are automatically initialized when they are declared.
2.  There are numerous methods for initializing objects based on the number of arguments passed during the declaration.
3.  The base class's constructors can be used to initialize child class objects.

Program:

#include<iostream.h>

#include<string.h>

class book
{ 
private: 
int bookno;
char bookname[20];

public:
book( )
{ 
bookno=10;
Strcpy(bookname,"programming in C++");
}
~book( )
{
cout<<"destructor called";
}
void showdetails( )
{
cout<<"book no:"<<bookno<<endl;
cout<<"bookname:"<<bookname<<endl;
}
};
void main( )
{
book b1;
b1.showdetails( );
}

Output: