Programmino C++ - Gestione di date

#include <iostream.h>

#include <stdlib.h>

class Date

{ //dati membro (giorno, mese, anno)

short int gg;

short int mm;

int aa;

public:

//costruttori e distruttori

Date() {gg=1;mm=1;aa=1999;};

Date(short int, short int, int);

~Date() {gg=mm=aa=0;};

//metodi

short int GetG() {return gg;}

short int GetM() {return mm;}

int GetA() {return aa;}

void SetG(short int g) {gg=g;}

void SetM(short int m) {mm=m;}

void SetA(int a) {aa=a;}

void Display();

void Input();

long int Convert();

};

Date::Date(short int d,short int o, int y)

{ gg=d;

mm=o;

aa=y;

}

void Date::Display()

{ cout<<gg<<"/"<<mm<<"/"<<aa<<endl;

}

void Date::Input()

{ cout<<"Inserire la Data (gg , mm ,aaaa):"<<endl;

cin>>gg>>mm>>aa;

if ((gg<=1)&&(gg>=31)&&(mm>=1)&&(mm>=12)&&(aa==0)) {

cout<<"Data inesistente!"<<endl;

exit (1);

}

}

long int Date::Convert()

{ long int giorni;

int d;

if ((gg>=1)&&(gg<=31)&&(mm>=1)&&(mm<=12)&&(aa!=0)) {

switch (mm) {

case 1 : d=0;

break;

case 2 : d=31;

break;

case 3 : d=59;

break;

case 4 : d=90;

break;

case 5 : d=120;

break;

case 6 : d=151;

break;

case 7 : d=181;