我有一个名为 Base
的抽象类我从中派生了一个类(Derived
),如下所示:
#include <iostream>
#include <string>
#include <memory>
class Base
{
public:
virtual void printClass()const = 0;
virtual ~Base(){}
};
class Derived: public Base
{
private:
int m_var1;
std::string m_var2;
public:
Derived() = default;
Derived(const int& v1, const std::string& v2)
:m_var1(v1), m_var2(v2)
{ }
void printClass()const override
{
std::cout << "Derived Class with\t";
std::cout << m_var1 << " " << m_var2 << std::endl;
}
~Derived(){ std::cout << "Derived destroyed" << std::endl; }
};
现在在main()
为了利用多态性,我可以声明如下:
int main()
{
std::shared_ptr<Base> Obj[3];
Obj[0] = std::make_shared<Derived>(1,"One");
Obj[1] = std::make_shared<Derived>(2,"Two");
Obj[2] = std::make_shared<Derived>(3,"Three");
for(const auto& it: Obj)
it->printClass();
return 0;
}
但是,我目前正在尝试了解有关 std::shared_ptr<>()
的更多信息及其自定义删除技术,我遇到了以下声明。
std::shared_ptr<Base> Obj(new Derived[3], [](Derived* obj){ delete[] obj; });
和
std::shared_ptr<Base> Obj(new Derived[3] = {
{1,"One"},
{2,"Two"},
{3,"Three"}
},
[](Derived* obj){ delete[] obj; });
我的问题是:
- 为什么我无法初始化或将值传递给
Derived
的构造函数按照以下方式上课,即使我有一个服装定义的构造函数可用于derived
类(class)?还是我错过了什么? - 如果是这样,初始化和访问的正确方法是什么
这样的
derived class
数组元素?
最佳答案
你可以这样调用构造器:
std::shared_ptr<Base> Obj{
new Derived[3]{ {1,"One"}, {2,"Two"}, {3,"Three"} },
[](Derived* obj){ delete[] obj; }
};
关于C++:如何初始化以下 std::shared_ptr 构造函数数组,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49718670/