7. Date.cpp

#include<iostream>
using namespace std;

class date
{
   private:int mm,dd,yy;
   public:void getdate();
          int operator -(date);
          date operator +(int);
};

void date::getdate()
{
    cout<<"Enter a valid date(dd mm yy):";
    START:
    cin>>dd>>mm>>yy;
    if((mm==2) && (dd>29)){
       cout<<"Wrong input!!!\n";
       cout<<"Enter the date again....\n";
       goto START;
   }
   if((mm>12)||(dd>31)){
       cout<<"Wrong input!!!\n";
       cout<<"Enter the date again....\n";
       goto START;
    }
   if((mm==4||mm==6||mm==9||mm==11) && (dd>30)){
       cout<<"Wrong input!!!\n";
       cout<<"Enter the date again....\n";
       goto START;
   } 
   if((yy%4)!=0 && (mm==2) && (dd>28)){
      cout<<"wrong input!!!\n";
      cout<<"Eenter the date again....\n";
       goto START;
    }
}
int date::operator -(date d2)
{
    int i,nod1,nod2,nody,lc,no_of_days;
    nod1=nod2=lc=0;
  for(i=1;i<mm;i++){
     if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)
     nod1+=31;
     else if(i==2)
     nod1+=28;
     else
     nod1+=30;
 }
    nod1+=dd;
 for(i=1;i<d2.mm;i++){
      if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)
      nod2+=31;
      else if(i==2)
      nod2+=28;
      else
      nod2+=30;
 }
   nod2+=d2.dd;
   nody=(yy-d2.yy)*365;

  for(i=d2.yy;i<yy;i++)
      if((i%4)==0)
      lc++;

  int y4=yy-d2.yy;
   while(y4>400){
         lc++;
         y4-=400;
 }
   if((mm>2) && (yy%4)==0)
        lc++;
    if((d2.mm>2) && (d2.yy%4)==0)
        lc--;
  no_of_days=nody+nod1-nod2+lc;
    if(no_of_days>0){
       cout<<"Total number of days between these dates is=";
   return(no_of_days);
 }
   else
    return(no_of_days);
}
date date::operator +(int nd)
{
     date dd3;
  while(nd>365){
      yy++;
      nd-=365;
 }
  while(nd>30){
      if(mm==1||mm==3||mm==5||mm==7||mm==8||mm==10||mm==12){
        nd-=31;
        mm++;
    }
      else if(mm==2){
        nd-=28;
        mm++;
   }
      else{
       nd-=30;
       mm++;
    }
      if(mm>12) {
        yy++;
        mm=1; 
    }
 }
    dd=dd+nd;
    if(dd>30){
      if(mm==4||mm==6||mm==9||mm==11){
          mm++;
         dd-=30;
   }
      else if(mm==2){
         mm++;
         dd-=28;
   }
     else if(dd>31){
         mm++;
         dd-=31;
 }
     if(mm>12){
         yy++;
         mm=1;
   }
 }

    dd3.mm=mm;
    dd3.dd=dd;
    dd3.yy=yy;
    cout<<"New date is:";
    cout<<dd<<"-"<<mm<<"-"<<yy<<endl;
      return(dd3);
}
int main()
{
   int res,num;
   date dd1,dd2;

 BEGIN:
    dd1.getdate();
    dd2.getdate();
     res=dd1-dd2;

 if(res<0){
      cout<<"The first date should be greater than the second date\n";
      cout<<"So enter the dates again\n";
      goto BEGIN;
 }
   cout<<res;
    cout<<"\nEnter the no. of days to be added to the FIRST date:";
    cin>>num;
    dd2=dd1+num;
}