c++ - 为什么 valgrind 显示泄漏，即使包含动态分配对象的 vector 已被释放？

Question

我已经使用 new 在堆上分配了一个 vector :

std::vector<t*> *vec = new std::vector<t*>;

此 vector 包含类“t”的类对象，这些类对象是使用 new 创建的

t *ptr1 = new t();
t *ptr2 = new t();
t *ptr3 = new t();
t *ptr4 = new t();

现在，当我删除 vector 时，预计添加到其中的所有这些对象也应该被销毁，我的意思是:

std::vector<t*> *vec = new std::vector<t*>;
 vec->push_back(ptr1);
 vec->push_back(ptr2);
 vec->push_back(ptr3);
 vec->push_back(ptr4);

ptr1、ptr2、ptr3、ptr4 指向的内存也应该被释放。

但 Valgrind 将其显示为泄漏!!! Valgrind 有问题吗？

==15634==
==15634== HEAP SUMMARY:
==15634==     in use at exit: 48 bytes in 8 blocks
==15634==   total heap usage: 12 allocs, 4 frees, 128 bytes allocated
==15634==
==15634== LEAK SUMMARY:
==15634==    definitely lost: 32 bytes in 4 blocks
==15634==    indirectly lost: 16 bytes in 4 blocks
==15634==      possibly lost: 0 bytes in 0 blocks
==15634==    still reachable: 0 bytes in 0 blocks
==15634==         suppressed: 0 bytes in 0 blocks
==15634== Rerun with --leak-check=full to see details of leaked memory
==15634==
==15634== For counts of detected and suppressed errors, rerun with: -v
==15634== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)

下面是完整的程序，供大家引用:

#include <iostream>
#include <vector>
using namespace std;

class t
{
int *ptr;
public:
  t()
  {
    cout << "t's constructor" << endl;
    ptr = new int(50);
  }
 ~t()
  {
    cout << "t's destructor called" << endl;
    delete ptr;
  }

  void func()
  {
     cout << "This is class t's function" << endl;
  }

};

//void func(int *ptr, t* ptr1)
void func(t* ptr1)
{
 //delete ptr;
 delete ptr1;
}

int main( )
{
 //int *ptr;

 t *ptr1 = new t();
 t *ptr2 = new t();
 t *ptr3 = new t();
 t *ptr4 = new t();
 //ptr =new int(20);
 //func(ptr, ptr1);
 //func(ptr1);

 std::vector<t*> *vec = new std::vector<t*>;
 vec->push_back(ptr1);
 vec->push_back(ptr2);
 vec->push_back(ptr3);
 vec->push_back(ptr4);

 delete vec;
 //delete ptr1; ===============> Are these required? Shouldn't delete vec take care?
// delete ptr2;
 //delete ptr3;
 //delete ptr4;

}

Answer 1

Now when i delete the vector, it's expected that all these objects which are added to it should get destroyed as well

它们是。您添加了指针，指针将被销毁。

不过，这并没有说明指针指向的东西。简而言之，您的假设是错误的。

您的选择:

• delete销毁 vector 之前的每个指针
• 使用智能指针
• 停止使用指针!停止使用动态分配!
  std::vector<t>在大多数情况下应该没问题。