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#include <iostream>
#include <string>
using namespace std;
// utilisation de la méthode
#define INTERN 0 // => OK
#define EXTERN 1 // => ERROR ???
#define OP_PLUS_EXT INTERN
// #define OP_PLUS_EXT EXTERN
// #define OP_PLUS_EXT BOTH
// #define BOTH 7 // BOTH les deux !! (test pour connaître le choix du compilo)
// error: use of overloaded operator '+' is ambiguous
// (with operand types 'Test' and 'Test')
class Test {
private:
int val;
string name;
public:
Test (string s="default", int v=-1);
Test (Test const&);
~Test ();
ostream& affiche (ostream& sortie) const;
// surcharge interne
Test& operator+= (Test const&);
Test& operator= (Test const&);
#if OP_PLUS_EXT == INTERN //|| OP_PLUS_EXT == BOTH
Test const operator+ (Test const&);
#endif
};
Test::Test (string s, int v)
// Test::Test( string s="default", int v=-1)
: name (s), val (v)
{
cout << "NEW val : " << s << " " << v << endl;
// cout << "NEW val : " << *this << endl;
}
Test::Test (Test const& t)
: name( t.name+"_dup"), val( t.val)
{
cout << "DUP val : " << name << " " << val << endl;
// cout << "DUP val : " << t << endl;
}
Test::~Test ()
{
cout << "DEL val : " << name << " " << val << endl;
}
// toujours intern
Test& Test::operator= (Test const& t)
{
cout << "OP = : " << name << " = " << t.name << endl;
// cout << "OP = : " << t << endl; // ERROR ???
// error: invalid operands to binary expression
// ('basic_ostream<char, std::__1::char_traits<char> >' and 'const Test')
// accès directe aux attributs name et val de la classe
name = name +"="+t.name;
val = t.val;
return *this;
}
Test& Test::operator+= (Test const& t)
{
cout << "OP+= : " << name << " += " << t.name << endl;
// cout << "OP+= : " << t << endl; // ERROR ???
// error: invalid operands to binary expression
// ('basic_ostream<char, std::__1::char_traits<char> >' and 'const Test')
val += t.val;
name = name+"+="+t.name;
return *this; // utile pour affectation à la suite : t3 = (t1+=t2);
// renvoie alors &t1 pour affectation dans t3
// pas la peine de créer une copie locale car t1 existe déjà
}
// méthode interne sans variable tmp
// ERROR : modifie l'instance courante
// car pas de copie d'effectuée. Idem à passage par référence
// Test const Test::operator+( Test const& t)
// {
// // cout << t1.val << endl; error: 'val' is a private member of 'Test'
// cout << "OP+ : " << name << " + " << t.name << endl;
// val += t.val;
// name = name+"+"+t.name;
// return *this;
// }
#if OP_PLUS_EXT == INTERN //|| OP_PLUS_EXT == BOTH
// méthode interne avec variable tmp : OK
Test const Test::operator+ (Test const& t)
{
cout << "OP+ INT : " << name << " + " << t.name << endl;
// cout << "OP+ INT : " << t << endl; // ERROR ???
// error: invalid operands to binary expression
// ('basic_ostream<char, std::__1::char_traits<char> >' and 'const Test')
Test tmp;
tmp.val = val + t.val;
tmp.name = name+"+"+t.name;
return tmp;
}
#endif
#if OP_PLUS_EXT == EXTERN //|| OP_PLUS_EXT == BOTH
// surcharge externe
Test const operator+(Test, Test const&);
const Test operator+ (Test t1, Test const& t2)
{
cout << "OP+ EXT : ";
// << t1.name << " + " << t2.name << endl; // ERROR => OK
// error: 'name' is a private member of 'Test'
// cout << t1 << endl; // ERROR ???
// error: invalid operands to binary expression ('ostream'
// (aka 'basic_ostream<char>') and 'Test')
t1 += t2; // passage par une méthode -> interne
return t1;
}
#endif
ostream& Test::affiche(ostream& sortie) const
{
sortie << "(" << name << " : " << val << ")";
return sortie;
}
ostream& operator<<(ostream& sortie, Test const& t)
{
return t.affiche( sortie);
}
/*
ces deux fonctions pour vérifier que cout << t;
s'excute sans erreur dans une fonction
*/
void display_ref(Test &);
void display_ref(Test &t){
cout << "display ref " << t << endl;
}
void display_val(Test);
void display_val(Test t){
cout << "display val " << t << endl;
}
int main()
{
Test t1("t1",1);
Test t2("t2",2);
cout << t1 << t2 << endl;
Test t3(t2);
cout << t3 << endl;
cout << "display_ref" << endl;
display_ref(t1);
cout << "display_val" << endl;
display_val(t1);
cout << "end display" << endl;
cout << "TEST1 + " << endl;
cout << (t1+t2) << endl;
cout << "TEST2 + " << endl;
Test t4("t4", 16);
cout << t4 << endl;
t4 = t1+t2;
cout << t4 << endl;
cout << "TEST1 +=" << endl;
Test t5("t5", 25);
t5 += t1;
cout << t5 << endl;
cout << "TEST2 +=" << endl;
t4 = {"aze", 13};
cout << t4 << endl;
cout << "END" << endl;
return 0;
} |
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