Question

In c++, is using a vector of objects a good idea? If not, what’s wrong with this c++ code?

#include <vector>

using namespace std;

class A {};

int main() {

        vector<A*> v ( new A);
        return 0;
}

from g++:

13: error: invalid conversion from
A*' tounsigned int’

Answer 1

The constructor for std::vector takes an initial length, not an element.

This means you’d normally do:

vector<A*> v(1); // Initialize to length 1
v.push_back( new A() ); // Add your element...

You’re getting the compiler error you are because, on your system, size_type is defined as an unsigned int. It’s trying to use that constructor, but failing, since you’re passing it a pointer to an A.