Re: Copy Constructors and Assignment Operator, When should I use?

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"rockdale" wrote:
[...]
I simply assign set1 to set2 like this
set2 = set1;

will this assignment will copy whatever in set1 to set2? (deep
copy,
even the vector items?),

Yes, it will copy everything, provided that set items have proper
copy constructor. The `std::vector' container can copy itself
without a problem.

well my coworker told me that I need to have a define my own
copy
constructor for ItemSet, ItemListA and ItemListB for it works
properly. in the copy contructor of ItemSet,

ItemSet(ItemSet& toCopy){
//copy constructor
a = toCopy.a;
b = toCopy.b;

}

notice a and b are classes that I defined, to enable a =
toCopy.a
works properly. I need to define copy contructor in my ItemListA
and
ItelListB classes, basically, to manually the vector from the
toCopy,
is his statement true?
[...]

No. Either he misunderstood your design or plain wrong about copy
constructors.

struct ItemA{
int aInt;
std::string aString;

} ;

struct ItemB{
int bInt;
std::string bString;
time_t bTime;

} ;

Both `ItemA' and `ItemB' classes don't need explicit copy
constructor since compiler generated cctor is good enough. The
`std::string' container knows how to copy itself and other types
are just fine with language provided copy.

class ItemSet{

ItemListA a;
ItemListB b;
...
};

The `ItemSet' class doesn't need cctor either since all its
members know how to copy themselves.

class ItemListA{
std::vector <ItemA> m_vecA;
...
};

class ItemListB{
std::vector <ItemB> m_vecB;
...
};

Both `ItemListA' and `ItemListB' classes don't need explicit copy
constructor since their only memebr is `std::vector', which has
proper cctor.

HTH
Alex


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