Find a class in vector of pointers to different classes

Question

So i have this:

class Grup : public Shape
{
private:
    std::vector<Shape *> continut;
public:
    static const std::string identifier;
    Grup(){};
    ~Grup(){
    continut.clear();
    };
    void add(Shape *);
    void remove(Shape *);
    void output(std::ostream &) const;
    void readFrom(std::istream &);
    void moveBy(int, int);
    friend std::ostream &operator<<(std::ostream &, const Grup &);
}

and i want to implement the remove function. i tried this:

void Grup::remove(Shape *s)
{
vector<Shape*>::iterator it;
it = continut.begin();
while(it!=continut.end())
{
    if((*it) == s)
    {
    it = continut.erase(it);
    }
    else it++;

}
}

but the == doesn't return me a true value. i also tried to overload the operator == on each shape but same result. what can i do?

Just two advices, use [`std::remove`](http://en.cppreference.com/w/cpp/algorithm/remove) instead of a `while` (why type an algorithm wich is already typed on the stl?) and don't clear the vector in the destructor, it will be cleared anyways. — PaperBirdMaster, Apr 15 '13 at 13:12
@makc i tried something like this: `bool Triunghi::operator==(const Triunghi& T) { if(this->identifier==T.identifier&&this- >p1.getX()==T.p1.getX()&&this->p1.getY()==T.p1.getY()&&this->p2.getX()==T.p2.getX()&&this->p2.getY()==T.p2.getY()&&this->p3.getX()==T.p3.getX()&&this->p3.getY()==T.p3.getY()) return 1; return 0; }` — user2116010, Apr 15 '13 at 19:54
@user2116010 what does the identifier represents? Did you try debugging this code and check which parameter wasn't equal? — makc, Apr 16 '13 at 08:19
@makc yes i tried and it didn't even enter this overload function — user2116010, Apr 16 '13 at 10:09
@user2116010 make sure you didn't run optimized code, this is your real problem solve the debug problem and you'll be able to figure out the overloading problem — makc, Apr 16 '13 at 12:23

score 1 · Answer 1 · edited May 23 '17 at 12:04

1

This is comparing the memory addresses of two Shape objects:

if((*it) == s) // '*it' is of type `Shape*`

it is not comparing two Shape objects. A further dereference is required to use operator== defined for Shape. However, see What's the right way to overload operator== for a class hierarchy? for a discussion on how to handle operator== for a class hierarchy.

edited May 23 '17 at 12:04

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answered Apr 15 '13 at 13:11

hmjd

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score 0 · Answer 2 · edited May 23 '17 at 11:50

0

you are comparing the shape pointers addresses and they are different.

you should overload operator ==

here are some examples:

C++ Operator Overloading Guidelines

Operator overloading

edited May 23 '17 at 11:50

Community

1
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answered Apr 15 '13 at 13:14

makc

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Find a class in vector of pointers to different classes

2 Answers2