在 C++ 中，如何编写析构函数来释放指向结构的指针的内存? [英] In C++, how to write a destructor for freeing memory of pointer to a structure?

问题描述

这是我的结构A

struct A {国际a1;国际a2;~A() { }};

B 是另一个包含指向 A 的指针的结构

 struct B {B(int b, A* a): b1(b), ptr2A(a){}国际b1;A* ptr2A;~B() {删除b1；//遍历 A 指向的每个元素，删除它们 <----}};

稍后我使用下面的代码

int bb1;向量<A*>aa1;//做一些事情B *ptrB = 新 B(bb1, aa1);

我需要删除/释放 ptrB 指向的所有内存.因此，我需要在 struct B 中编写正确的析构函数.如何遍历 A 指向的每个元素并删除它们?

解决方案

如果您使用的是 C++11 编译器，只需使用 std::shared_ptr，您就不必担心删除.这是因为 shared_ptr 是一个智能"指针，它会自动删除它所指向的内容.

#include 结构体B{国际b1;std::shared_ptrptr2A;B(int b, std::shared_ptr a):b1(b),ptr2A(a)({}~B(){}//你看！没有删除！};

每当你分配一些东西时使用共享指针:

#include...{....std::shared_ptrptrB( 新 B(bb1, aa1) );//这是另一种更易读的方法来做同样的事情://auto ptrB = std::make_shared(bb1,aa1);...}//这里没有内存泄漏，因为B被自动销毁

这里有更多关于智能指针主题的信息.>

我还应该提到，如果您没有 C++11 编译器，您可以从 BOOST 库.

Here's my structure A

struct A {
    int a1;
    int a2;
    ~A() { }
};

B is another structure that contains a pointer to A

 struct B {
    B(int b, A* a)
      : b1(b), ptr2A(a)
    {}
    int b1;
    A* ptr2A;

    ~B() {
         delete b1;
         // traverse each element pointed to by A, delete them <----
    }
};

Later on I use below code

int bb1;
vector <A*> aa1;
// do some stuff
B *ptrB = new B(bb1, aa1);

I need to delete/free all the memory pointed to by ptrB. Hence I need to write correct destructor inside struct B. How do I traverse each element pointed to by A and delete them?

解决方案

If you're using a C++11 compiler, just use std::shared_ptr and you don't have to worry about deletes. This is because the shared_ptr is a "smart" pointer that will automatically delete what its pointing to.

#include <memory>
struct B 
{
    int b1;
    std::shared_ptr<A> ptr2A;
    B(int b, std::shared_ptr<A> a):b1(b),ptr2A(a)({}
    ~B(){} //look ma! no deletes!
};

Use a shared pointer whenever you allocate something:

#include<memory>
...
{
    ....
    std::shared_ptr<B> ptrB( new B(bb1, aa1) );
    //Here is another, more readable way of doing the same thing:
    //auto ptrB = std::make_shared<B>(bb1,aa1);
    ...
}
//no memory leaks here, because B is automatically destroyed

Here's more info on the subject of smart pointers.

I should also mention that if you don't have a C++11 compiler, you can get shared pointers from the BOOST library.

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