C++：析构函数和指针

Question

In my class C, there is a pointer (var_a) to a class A, so in the destructor of C, I write "delete var_a". In vscode, the code works but doesn't stop automatically after the end of the main. Also, the line where var_a is deleted, is highlighted in yellow. The debug console print:

Warning: Debuggee TargetArchitecture not detected, assuming x86_64.
=cmd-param-changed,param="pagination",value="off"

The hpp:

#ifndef DEF_TEST4
#define DEF_TEST4

#include <iostream>
#include <string>


class A
{   public:
    A();
    A(A const& copy_a);
    virtual std::string printer();
    protected:
    std::string var;
};

class B : public A
{
    public:
    B();
    B(B const& copy_b);
    virtual std::string printer();
    protected:
    std::string var;
};

class C
{
    public:
    C(A* a);
    ~C();
    virtual A* get_a();
    protected:
    A* var_a;
};

#endif

The cpp:

#include "test4.hpp"


A::A() : var("a")
{}

B::B() : var("b")
{}


A::A(A const& copy_a) : var(copy_a.var)
{}

B::B(B const& copy_b) : var(copy_b.var)
{}


std::string A::printer()
{
    return var;
}

std::string B::printer()
{
    return var;
}

C::C(A* a) : var_a(a)
{}

C::~C()
{
    delete var_a;
}

A* C::get_a()
{
    return var_a;
}

The main cpp:

#include "test4.hpp"
#include "test4.cpp"
#include <typeinfo>

int main()
{
    A ca;
    B cb;
    B cb2(cb);
    C cc(&ca);
    C cc2(&cb);

    std::cout << ca.printer() << std::endl;
    std::cout << cb.printer() << std::endl;
    std::cout << cb2.printer() << std::endl;
    std::cout << cb2.A::printer() << std::endl;
    std::cout << cc.get_a()->printer() << std::endl;
    std::cout << cc2.get_a()->printer() << std::endl;
    std::cout << "type cc2.get_a() : " << &typeid(cc2.get_a()) << std::endl;
    std::cout << "type ca : " << &typeid(ca) << std::endl;
    std::cout << "type cb : " << &typeid(cb) << std::endl;

    cc.~C();

}

I suppose that there is a problem, but what? Sorry for the possible bad english, it's not my mother tongue. Thanks for your help.

Answer 1

As the comments have suggested, there are two problems in the code.

First, cc.~C() : don't ever call destructors explicitly. There are situations where that's appropriate, but those are far in your future. The compiler will call the destructor when cc goes out of scope. You don't need to do it yourself.

Second, in cc and cc2 , var_a points at an object that was not created with new ; don't delete it. Just remove that delete var_a; from C::~C() . The objects that var_a points at will also be destroyed when they go out of scope. You don't need to do it yourself.