Compilation error in C++ while performing operator overloading - c++

Question

I am learning c++ and getting the compilation error while doing operator overloading. I am attaching my code. Please have a look. The error is at line no 27.
I tried to make changes but as I am totally new to c++, I am unable to resolve this. We don't have anything like this in C.
Also, suggest me some good way to improve my coding standard and skills.
#include <iostream>
#include<string>
#include <string.h>
#include <stdlib.h>
using namespace std;
class rectangle
{
private:
int l,b;
public:
// friend
rectangle(int,int);
rectangle(rectangle &r);
void setL(int);
void setB(int);
int getL();
int getB();
int area();
int parameter();
void isSquare();
rectangle operator + (rectangle r1)
{
rectangle temp; // compilation error here ///////Line No 27:
temp.l=r1.l+l;
temp.b=r1.b+b;
return temp;
}
// void ~rectangle();
};
void rectangle:: isSquare()
{
if(l==b)
cout<<"It is square"<<endl;
else
cout<<"It is rectangle"<<endl;
}
rectangle:: rectangle(int length =0, int breadth =0)
{
setL(length);
setB(breadth);
}
rectangle:: rectangle(rectangle &r)
{
setL(r.l);
setB(r.b);
}
void rectangle::setL(int length)
{
if(length>0)
l=length;
else
l=0;
}
void rectangle::setB(int breadth)
{
if(breadth>0)
b=breadth;
else
b=0;
}
int rectangle::getL()
{
return l;
}
int rectangle::getB()
{
return b;
}
int rectangle::area()
{
return l*b;
}
int rectangle::parameter()
{
return 2*l*b;
}
//extern void print(char *s);
int main()
{
cout<<("Welcome to test codes!!! :) :) \n");
rectangle r(10,5);
rectangle r1(2,5);
rectangle r2;
cout<<"r "<<r.area()<<' '<<r.parameter()<<endl;
cout<<"r1 "<<r1.area()<<' '<<r1.parameter()<<endl;
cout<<"r2 "<<r2.area()<<' '<<r2.parameter()<<endl;
r.isSquare();
r2=r+r1;
cout<<"r2 "<<r2.area()<<' '<<r2.parameter()<<endl;
return 0;
}
Error is main.cpp:32:19: error: no matching function for call to 'rectangle::rectangle()'
rectangle temp;

Answer 1

Look at your constructors
rectangle(int,int);
rectangle(rectangle &r);
One that takes two integers, and one that takes another rectangle. So this means to construct a rectangle you must provide either two integers or another rectangle.
Now look at the line with the error
rectangle temp;
What's provided here? Nothing of course, but you don't have a constructor with no arguments, so this is a compilation error.
Looking at your code the best solution is this
rectangle temp(r1.l+l, r1.b+b);
return temp;
Now two integers are being provided.
BTW your code shows a complete lack of awareness of const. You're going to quickly run into trouble unless you learn about that.

Answer 2

The line
rectangle temp; // compilation error here ///////
is trying to create a new instance of "rectangle" without any constructor parameters. Your class does not have a constructor that takes no parameters, that's why you get the error. It has nothing to do with your operator.
You need to use:
rectangle temp(0, 0);
Or, create a constructor that takes no parameters:
in header
rectangle();
in source file
rectangle:: rectangle() {}