c++基类未指定virtual虚函数，内存泄漏示例

当析构函数不加上virtual时，基类指针指向派生类delete时，不会调用派生类的析构函数，造成内存泄漏。
基类的析构函数加上virtual之后，当要调用基类的析构函数时，编译器会从虚函数表中找到要执行的正确的函数地址，即派生类的析构函数去调用。

无内存泄漏

#include 

#define debug qDebug()<<
class Base
{
public:
    Base() {}
    virtual ~Base()
    {
        std::cout << "基类析构" << std::endl;
    }
};
 
class Derived : public Base
{
public:
    Derived() {};
    ~Derived()
    {
        std::cout << "派生类析构" << std::endl;
    }
};

int main(int argc, char *argv[])
{
    Base * pbase = new Base;
    delete pbase;

    std::cout << "------------" << std::endl;

    pbase = new Derived;
    delete pbase;
}

有内存泄漏

#include 

#define debug qDebug()<<
class Base
{
public:
    Base() {}
    ~Base()
    {
        std::cout << "基类析构" << std::endl;
    }
};
 
class Derived : public Base
{
public:
    Derived() {};
    ~Derived()
    {
        std::cout << "派生类析构" << std::endl;
    }
};

int main(int argc, char *argv[])
{
    Base * pbase = new Base;
    delete pbase;

    std::cout << "------------" << std::endl;

    pbase = new Derived;
    delete pbase;
}