CODEWITHSUNDEEP
c++vectoriterator
user1018517
user1018517

Reputation:

Strange error @ Visual Studio C++

this:

Polygon::Polygon(const Polygon & polygon) {
    for (vector<Point*>::iterator it = polygon._points.begin(); it != _points.end(); it++)
        _points.push_back(*it);
}

gives me an error of 

C2440 'initializing': cannot convert from 'std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<Point *>>>' to 'std::_Vector_iterator<std::_Vector_val<std::_Simple_types<Point *>>>

While this works:

Polygon::Polygon(const Polygon & polygon) {
    vector<Point*> points = polygon._points;
    for (vector<Point*>::iterator it = points.begin(); it != _points.end(); it++)
        _points.push_back(*it);
}

Upvotes: 0

Views: 470

Answers (1)

Eran
Eran

Reputation: 22020

You're taking a const Polygon as an argument. On the first case, your iterator is therefore const. On the second case, you're assigning the const polygon.vector into a local, non-const vector, which makes it possible to get a non-const iterator.

Take a look at what your code is actually doing: you're taking a polygon that you promise not to modify, and trying to insert points into it. Since that's what you're doing, better drop the const from the argument.

Upvotes: 1

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