Exercice 4 corrigé la surcharge des opérateurs en langage C++

#include <iostream.h>
class date{
int jj;
int mm;
public:
date(int jour=0, int mois=0); // pas oublier d'initialiser sinon ca pose probleme
friend date operator-(date d1, date d2);
friend date operator+(date d1,date d2);
friend istream& operator>>(istream& tmp,date& d);
friend ostream& operator<<(ostream& tmp,date d);
date operator --(int);
date& operator --();
date operator ++(int);
date& operator ++();
void lire();
void affiche();
};
date::date(int jour, int mois){
jj=jour;
mm=mois;
}
date operator+(date d1, date d2){
date result;
result.jj=d1.jj+d2.jj;
result.mm=d1.mm+d2.mm;
return result;
}
date operator-(date d1, date d2){
date result;
result.jj=d1.jj-d2.jj;
result.mm=d1.mm-d2.mm;
return result;
}
istream& operator>>(istream& tmp,date& d){
cout<<"Entrez la date svp"<<endl;
tmp>>d.jj;
tmp>>d.mm;
return tmp;
}
ostream& operator<<(ostream& tmp,date d){
cout<<endl;
cout<<"Voici la date"<<endl;
tmp<<d.jj;
cout<<" / ";
tmp<<d.mm;
return tmp;
}
date date ::operator--(int){// attention au placement du ::
date tmp=*this;
tmp.jj--;
tmp.mm--;
return tmp;
}
date& date::operator --(){
jj--;
mm--;
return *this;
}
date date ::operator++(int){// attention au placement du ::
date tmp=*this;
tmp.jj++;
tmp.mm++;
return tmp;
}
date& date::operator ++(){
jj++;
mm++;
return *this;
}
void date::lire(){
cout<<"Entrer le jour : "<<endl;
cin>>jj;
cout<<"Entrer la date : "<<endl;
cin>>mm;
}
void date::affiche(){
cout<<" le resultat de l'operation sur les dates "<<endl;
cout<<jj<<" / "<<mm<<endl;
}
void main(){
date a;
date b;
date c;
a.lire();
//b.lire();
cin>>b;
c=a+b;
c.affiche();
c=a-b;
cout<<c;
c--;
--c;
c.affiche();
++c; // on utilisera cette operation
c++;
c.affiche();
}