## Rayanjaha

Hi guys !
I am trying to find out how to do this problem using construction with useful value , here is

Can I use cons traction with

``````public :
void set_value (int e, int r)

{
q=e;
w=r;
}``````

My code

``````
/*
Q: Write a C++ program to print the area of rectangle using class constructor?

*/
#include<iostream>
using namespace std;

class rectangle
{
int q,w ;
char o;
public :
void set_value (int e, int r)

{
q=e;
w=r;
}
rectangle();    // my construction
int area()

{
return q*w ;
}

};
Rectangle::rectangle ()// I could not do it with useful values so I use this sentence
{
cout<<"Welcome to Area Calulater \n\n";

}
int main()
{
int t,y,u;
char i;
rectangle rect;
cout << "Enter a length:\n";
cin>>t;
cout << "Enter a width:\n "  ;
cin >> y;
rect.set_value(t,y);
u = rect.area();
cout<< "area of the rectangle ="<<u;
cin>>i;
return 0;
}``````

## sundip -3

``````/*
Q: Write a C++ program to print the area of rectangle using class constructor?

*/
#include<iostream>
using namespace std;

class rectangle
{
int q,w ;
char o;
public :
rectangle(int e=0, int r=0)
{
q=e;
w=r;
}
int area()

{
return q*w ;
}

};

int main()
{
int t,y,u;
char i;
;
cout << "Enter a length:\n";
cin>>t;
cout << "Enter a width:\n "  ;
cin >> y;
rectangle rect(t,y);
u = rect.area();
cout<< "area of the rectangle ="<<u;
cin>>i;
return 0;
}``````

## Rayanjaha

why did you give 0s?

``public :               rectangle(int e=0, int r=0)               {                           q=e;                           w=r;               }``

## sundip -3

``rectangle(int e=0, int r=0)``

Means default value of e and r are 0 and 0. So you can call same constructor in number of ways.

``````rectangle r1(); // q=0,w=0
// or
rectangle r2(4); // q=4,w=0
// or
rectangle r3(4,3); // q=4,w=3``````

## Rayanjaha

i got it , thanks a lot

## mshauny 25

or you can use a version similar to this one :

``````class Rectange
{
private:
int q,w;
char o;
void ToString();
public:
Rectange(int,int);
};

void Rectange::ToString()
{
cout << "Q >> " << q << " W >> "  << w << endl;
}

Rectange::Rectange(int qq=0,int ww=0)
{
q = qq;
w = ww;
ToString();
}``````

## Rayanjaha

``````/*
Q: Write a C++ program to print the area of rectangle using class constructor?

*/
#include<iostream>
using namespace std;

class rectangle
{
int q,w ;
char o;
public :
rectangle(int e=0, int r=0)
{
q=e;
w=r;
}
int area()

{
return q*w ;
}

};

int main()
{
int t,y,u;
char i;
;
cout << "Enter a length:\n";
cin>>t;
cout << "Enter a width:\n "  ;
cin >> y;
rectangle rect(t,y);
u = rect.area();
cout<< "area of the rectangle ="<<u;
cin>>i;
return 0;
}``````

what is this ?

``````int main()
{
int t,y,u;
char i;
;
cout << "Enter a length:\n";
cin>>t;
cout << "Enter a width:\n "  ;
cin >> y;
rectangle rect(t,y);    /* what is this line? creating object rect? if so where is       calling the  constructore? ?  like object_name. function_name*/
u = rect.area();
cout<< "area of the rectangle ="<<u;
cin>>i;
return 0;
}``````

## sundip -3

Line 10 create a object of "rectangle" and will call constructor internally.