using overloaded operator = for copying a vector of objects

Question

I try to copy the vector comanda to the vector comenzi :

 public :
        Ospatar(char nume[30],Comanda * comanda,int nrcom,char sex,int varst)
        {
            strcpy(Nume,nume);

            comenzi=new Comanda[sizeof(comanda)];
            for(int i=0;i<sizeof(comanda);i++)
            {
                comenzi[i]=comanda[i];

            }
            cout<<endl;

            nrComenzi=nrcom;
            gen=sex;
            varsta=varst;

        }

And here is the overloaded operator from Class Comanda :

Comanda& operator=(Comanda  c)
    {
        Prod.set_denProd(c.Prod.get_denProd());

        Num=c.Num;
        nrPortii=c.nrPortii;
        date.zi=c.date.zi;
        date.luna=c.date.luna;
        date.an=c.date.an;

    }

the first two elements of vector comanda are well transfered to vector comenzi but after that i get some random numbers ...

The correct overloading of ``operator=`` is ``T& operator=(const T& t)`` — nefas, May 26 '17 at 10:08
@nefas has a point; not taking reference means that a copy constructor will also be called, something you probably don't want. — Paul Stelian, May 26 '17 at 10:10
@NickyC If she's in my college, year 1, she probably doesn't really have that option — Paul Stelian, May 26 '17 at 10:10
@PaulStelian,thank you for your answear,but it still doesn't work,same problem — Oana, May 26 '17 at 10:16
@Oana Either way this code doesn't look that safe for C++ code... I think my Facebook profile is visible on my account here, maybe you can contact me separatel — Paul Stelian, May 26 '17 at 10:22
@Oana Hint: `sizeof(comanda)` doesn't do what you think it does. I'll reopen your question, but please leave us with a [MCVE]. Also you should inspect your program with the debugger stepping through line by line and watch the variables. — πάντα ῥεῖ, May 26 '17 at 10:24

score 0 · Answer 1 · answered May 26 '17 at 11:24

Generally you should use std::vertor -- this is the right way to do that in C++. But assuming that you're not allowed to use standard library:

First your Comanda::operator= should take argument via reference (preferably reference to const):

Comanda& operator=(const Comanda& c)

Then, sizeof(comanda) returns size of pointer to Comanda, not number of elements in the array. You generally have to pass the size of the array in separate argument (I guess nrcom is the one).

So:

comenzi = new Comanda[nrcom];
for (int i=0; i<nrcom; i++)

etc...

You'll of course need to clean the code more (what's that strcpy thing), and last but not least don't forget to add delete [] for your allocated data.

using overloaded operator = for copying a vector of objects

1 Answers1