[cdl-studenti] [OOP] Eliberare automata de memorie.

[marius Dragus]

Pai operatorul + nu ar trebui sa modifice obiectul curent.
De exemplu pe stringuri:

string x ="ana";
string y ="are";
string z = x+y;

cout<< x; //afiseaza "ana", x nu e modificat.


2010/3/6 Dan-George Filimon <dangeorge.filimon at gmail.com>

> Nu inteleg de ce ai in definitia operatorului + o noua alocare de memorie.
> De ce nu folosesti pointerul this?
>
> Cand faci un operator ca + m-as gandi ca ai ceva de genul:
> mine operator+(const mine x) {
>         memcpy(this->u, x.u, 10000 * sizeof(int));
>        return *this;
> }
>
> Asta nu ar face ce vrei?
>
> On Mar 6, 2010, at 4:20 PM, marius Dragus wrote:
>
> > Salut,
> >
> > Incerc sa scriu o clasa "mine" in C++ care sa permita operatorul +.
> > Problema este ca fiecare obiect aloca dinamic un array, iar o operatie de
> genul x =a +b+c ar cauza memory leak-uri.
> >
> > Cum s-ar putea face asta?
> >
> > Mai jos este codul. Mentin un contor al constructorilor/destructorilor,
> si se vede evident ca se obtin memory leakuri.
> >
> > Mersi,
> > Marius
> >
> > /*************************CODE*********************/
> >
> > #include <iostream>
> >
> > int count = 0;
> > using namespace std;
> >
> > struct mine
> > {
> >     int * u;
> >     mine()
> >     {
> >     u = new int[10000];
> >     count++;
> >     }
> >
> >     ~mine()
> >     {
> >     delete[] u;
> >     count--;
> >     }
> >
> >     mine & operator=(const mine & x)
> >     {
> >     //cout << "assign" << endl;
> >     u = x.u;
> >     }
> >
> >
> > };
> >
> > mine& operator+(const mine & x, const mine &y)
> > {
> >     mine * ret = new mine;
> >     return *ret;
> > }
> >
> > int main()
> > {
> >
> >     mine a, b, c, d;
> >     mine e;
> >
> >
> >     for (int i = 0; i<10; i++)
> >     {
> >     e = a + b + c + d;
> >
> >     }
> >
> >     cout << count << "\n"; // afiseaza 35 desi ar trebui sa fie 5
> >
> >     return 0;
> > }
> >
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