C++ Constructor overloading

Constructor overloading

Function overloading can be applied for constructors, as constructors are special functions of classes. A class can have more than one constructor with different signature. Constructor overloading provides flexibility of creating multiple type of objects for a class.

Illustration 15.4 constructor overloading

Compiler identifies a given member function is a constructor by its name and the return type.

#include<iostream>

using namespace std;

class add

{

int num1, num2, sum;

public:

add()

{

cout<<"\n Constructor without parameters.. ";

num1= 0;

num2= 0;

sum = 0;

}

add ( int s1, int s2 )

{

cout<<"\n Parameterized constructor... ";

num1= s1;

num2=s2;

sum=0;

}

add (add &a)

{

cout<<"\n Copy Constructor ... ";

num1= a.num1;

num2=a.num2;

sum = 0;

}

void getdata()

{

cout<<"\nEnter data ... ";

cin>>num1>>num2;

}

void addition()

{

sum=num1+num2;

}

void putdata()

{

cout<<"\n The numbers are..";

cout<<num1<<'\t'<<num2;

cout<<"\n The sum of the numbers are.. "<< sum;

}

};

int main()

{

add a, b (10, 20) , c(b);

a.getdata();

a.addition();

b.addition();

c.addition();

cout<<"\n Object a : ";

a.putdata();

cout<<"\n Object b : ";

b.putdata();

cout<<"\n Object c.. ";

c.putdata();

return 0;

}

Output

Constructor without parameters..

Parameterized constructor...

Copy Constructor ...

Enter data ... 20 30

Object a :

The numbers are..20 30

The sum of the numbers are.. 50

Object b :

The numbers are..10 20

The sum of the numbers are.. 30

Object c..

The numbers are..10 20

The sum of the numbers are.. 30

Illustration 15.5 to find the perimeter of a rectangle using constructor overloading in a class.

//constructor declared as outline member function

#include<iostream>

using namespace std;

class Perimeter

{

int l, b, p;

public:

Perimeter ();

Perimeter (int);

Perimeter (int,int);

Perimeter (Perimeter&);

void Calculate();

};

Perimeter :: Perimeter ()

{

cout<<"\n Enter the value of length and breath";

cin>>l>>b;

cout<<"\n\nNonParameterizd constructor ";

}

Perimeter ::Perimeter (int a)

{

l=b=a;

cout<<"\n\n Parameterizd constructor with one argument ";

}

Perimeter ::Perimeter (int l1, int b1)

{

cout<<"\n\n Parameterizd constructor with 2 argument ";

l=l1;

b=b1;

}

Perimeter ::Perimeter (Perimeter &p)

{

l= p.l;

b= p.b;

cout<<"\n\n copy constructor ";

}

void Perimeter ::Calculate(){

p = 2*(l+b);

cout<<p;

}

int main ()

{

Perimeter Obj;

cout<<"\n perimeter of rectangle is ";

Obj. Calculate ();

Perimeter Obj1(2);

cout<<"\n perimeter of rectangle ";

Obj1.Calculate ();

Perimeter Obj2 (2, 3);

cout<<"\n perimeter of rectangle ";

Obj2.Calculate ();

Perimeter obj3 (Obj2);

cout<<"\n perimeter of rectangle ";

obj3.Calculate ();

return 0;

}

Output

Enter the value of length and breath 10 20

Non Parameterizd constructor

perimeter of rectangle is 60

Parameterizd constructor with one argument

perimeter of rectangle 8

Parameterizd constructor with 2 argument

perimeter of rectangle 10

copy constructor

perimeter of rectangle 10