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[英]Transform vector of reference wrapper to Base class to vector of reference_wrapper to Derived class cannot dynamic cast
[英]Transform std:vector<reference_wrapper<Base>> to std:vector<reference_wrapper<Derived>> Runtime error time: 0 memory: 3412 signal:6
我正在尝试将对基础对象的引用向量转换为对派生对象的引用向量。 一切都编译良好,但我收到此错误:运行时错误时间:0内存:3412 signal:6
这是我的代码:
#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;
}
dynamicCast()函数怎么了?
编辑:@John Zwinck答案有所帮助,但是当我尝试在我的代码中执行此操作时,出现编译错误:
无法将'(&obj)-> std :: reference_wrapper <_Tp> :: get()'(类型为'MEPObject'类型)'动态转换为'类MEPGene&'(目标不是指针或对完整类型的引用)基因。 (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()));
}
}
^
dynamicCast()
。 问题在这里:
numbers.push_back(new B(2*i));
您只能构造作为基类的B
实例。 您不可能将它们D
为派生类D
也许您打算构造派生实例并将其存储在对base的引用向量中。
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