I am trying to convert vector of references to Base objects to vector of references to Derived objects. Everything is compiling fine, but i got this error: Runtime error time: 0 memory: 3412 signal:6
This is my code:
#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
using namespace std;
struct B {
B(int i) { b = i; }
virtual ~B() {}
int b;
};
struct D: public B {
D(int i): B(i) {}
};
typedef vector<reference_wrapper<B>> refB;
typedef vector<reference_wrapper<D>> refD;
void dynamicCast(refB &b, refD &d)
{
for(const auto& bb: b)
{
d.push_back(dynamic_cast<D&> (bb.get()));
}
}
int main() {
vector<B*> numbers;
refB refNumbers;
refD dNumbers;
for(int i = 0; i < 10; i++)
{
numbers.push_back(new B(2*i));
refNumbers.push_back(*numbers[i]);
}
dynamicCast(refNumbers, dNumbers);
return 0;
}
What is wrong with dynamicCast() function?
EDIT: @John Zwinck answer helped, but when i try to do this in my code i got compilation error:
cannot dynamic_cast '(& obj)->std::reference_wrapper<_Tp>::get()' (of type 'class MEPObject') to type 'class MEPGene&' (target is not pointer or reference to complete type) genes.push_back(dynamic_cast (obj.get()));
class MEPObject;
class MEPGene;
typedef std::vector<std::reference_wrapper<MEPObject>> MEPObjects;
typedef std::vector<std::reference_wrapper<MEPGene>> MEPGenes;
void dynamicCast(MEPObjects &objects, MEPGenes &genes)
{
for(const auto &obj: objects)
{
genes.push_back(dynamic_cast<MEPGene&> (obj.get()));
}
}
^
Nothing is wrong with dynamicCast()
. The problem is here:
numbers.push_back(new B(2*i));
You only ever construct instances of B
which is the base class. You can't possibly cast them to D
which is the derived class.
Perhaps you meant to construct derived instances and store them in your vector of references to base.