How can I use constructor and copy constructor and destructor for this program?

Question

Class line
{
Public:
Int getlength (void);
Line(int len);
Line(const line &obj);
~line();
Private:
Int *ptr;
};
Line::line(int len)
{
Cout<<"normal constructor allocating ptr"<<endl;
.........................?
}
Line::line(const line &obj)
{
Cout<< "copy constructor allocating ptr"<<endl;
........................?
}
Line::~line(void)
{
Cout<<"freeing memory"<<endl;
........................?
}
........? Are the parts that I don't know what should I put there

Answer 1

//you have it already but just trying to complete code
//read the comments to understand and about changes

#include<iostream>
using namespace std;

class line
{
public:
int getlength (void);
line();
line(int len);
line(const line &obj);
~line();

private:
int *ptr;
};

//default constructor
line::line()
{
ptr=new int; //setting 0
cout<<"normal constructor allocating ptr"<<endl;
}

line::line(int len)
{
ptr=new int(len); //setting value len
cout<<"normal constructor allocating ptr"<<endl;
}

//length function
int line::getlength(void)
{
return *ptr;
}

//copy constructor
line::line(const line &obj)
{
cout<< "copy constructor allocating ptr"<<endl;
}

line::~line(void) //distructor
{
cout<<"freeing memory"<<endl;

}

//main method
int main() {

line l1; //calling default constructor
line l2(55); //parameter constructor

cout<< l1.getlength() << endl; //output 0
cout<< l2.getlength() << endl; //output 55

//destructor called automatically now for both l1, l2 objects.

}