A program in C++ to create a Class Date and add and subtract two valid dates. Illustrate the use of copy constructor.

#include<iostream.h>

#include<conio.h>

class date

{private:int d;

             int m;

             int y;

 public:date()

            {d=0;m=0;y=0;}

            date(int a,int b,int c)

            {d=a;m=b;y=c;}

             void getdata();

             void showdata()

             {
             
cout<<"\n the date -> "<<d<<":"<<m<<":"<<y<<".";

              cout<<"\n";

             }

             void sum(date a,date b)

             {d=a.d+b.d;

              m=a.m+b.m;

              y=a.y+b.y;

             }

             void diff(date a,date b)

             {d=a.d-b.d;

              m=a.m-b.m;

              y=a.y-b.y;

             }

}d1,d2,d3;

void date :: getdata()

{int c=0,k=0,t;

 float l;

 clrscr();

 while(c==0)

 {cout<<"\n enter the parameters of date \n";

  cout<<"\n enter year: ";

  cin>>y;

  if(y>31000 || y<-31000)

  {cout<<"\n please enter the value within computational limit bet. -31000 and 31000)";

  }

  else

  {l=y%100;

   if(l==0)

   {t=y/100;

    l=t%4;

    if(l==0)

    {k=1;}

   }

   else

   {l=y%4;

    if(l==0)

    {k=1;}

   }

   c=1;

  }

 }

 c=0;

 while(c==0)

 {cout<<"\n enter month(1-12): ";

  cin>>m;

  if(m<1 || m>12)

  {cout<<"\n you have entered wrong value enter again";

  }

  else

  {c=1;}

 }

 l=0;

 while(c==1)

 {cout<<"\n enter date: ";

  cin>>d;

  if(m==1 || m==3 || m==5 || m==7 || m==8 || m==10 || m==12)

  {if(d<1 || d>31)

   {cout<<"\n sorry you have entered wrong value enter again";

   }

   else

   {c=0;}

  }

  else

  if(m==2 || m==4 || m==6 || m==9 || m==11)

  {if(d<1 || d>30)

   {cout<<"\n sorry you have entered wrong value enter again";

   }

   else

   {c=0;}

  }

  else

  {if(m==2)

   {if(k==1)

    {if(d<1 || d>29)

     {cout<<"\n sorry you have entered wrong value enter again";

     }

     else

     {c=0;}

    }

   }

   else

   if(d<1 || d>28)

   {cout<<"\n sorry you have entered wrong value enter again";

   }

   else

   {c=0;}

  }

 }

}

void main()

{int n,i;

 clrscr();

 d1.getdata();

 d1.showdata();

 d2.getdata();

 d2.showdata();

 d3.sum(d1,d2);

 d3.showdata();

 d3.diff(d1,d2);

 d3.showdata();

 getch();

}