Default Constructor

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Default Constructor

Default constructor is the constructor that can be called with no arguments but can have
default arguments.

These are further divided into following parts :

- Default constructor by the compiler.
-Default constructor (provided by the programmer).
-Default constructor with default arguments( provided by programmer).

-Default constructor by the compiler :

When the user doesn't provide any constructor, then the compiler automatically supplies
a default constructor having no arguments.


Example :

#include <iostream.h>
#include <conio.h>

class Account
{
private:
int account_no;

public :

void read()
{
account_no=10;
}

void display()
{
cout<< "Account number is : "<< account_no;
}
};

void main()
{
clrscr();

class Account acc;
acc.read();
acc.display();

getch();
}

Output :







-Default constructor (provided by the programmer) :

The programmer can also specify the default constructor without any parameters.

Example :


#include <iostream.h>
#include <conio.h>

class Account
{
private:

int account_no;

public :

Account()
{
account_no=10;
}

void display()
{
cout<< "Account number is : "<< account_no;
}
};

void main()
{
clrscr();

class Account acc;

acc.display();

getch();
}

Output :








-Default constructor with default arguments( provided by programmer) :

In this, the programmer provides atleast one default parameter to the constructor.


Example :

#include <iostream.h>
#include <conio.h>

class Account
{
private:

int account_no;

public :

Account(int x=10)//default constructor with argument
{
account_no=x;
}

void display()
{
cout<< "Account number is : "<< account_no;
}
};

void main()
{
clrscr();

class Account acc;

acc.display();

getch();
}

Output :

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