OOP | Question

v06-l4-dealocateOrder

(1/1)

When a std::vector is deallocated, in which order does it free its elements

from last element to first element

from first element to last element

depends on the compiler

depends on the C++ standard

???

This can be checked using this example code :

#include <iostream>
#include <vector>

using std::cout, std::endl;
using std::vector;

bool printMsg = false;

class Object {
public:
   ~Object() {
      if (printMsg) cout << "Destructing Object at " << this << endl;
   }
};

int main() {
   vector<Object> list;
   {
      Object o1;
      Object o2;
      Object o3;
      cout << "Creating list ..." << endl;
      list.push_back(o1);
      list.push_back(o2);
      list.push_back(o3);
   }
   printMsg = true;
   cout << "Vector is full :" << endl;
   cout << " -- first  object at " << &list[0] << endl;
   cout << " -- second object at " << &list[1] << endl;
   cout << " -- third  object at " << &list[2] << endl;
   cout << "End of program, dealocating vector ..." << endl;
   return 0;
}

which returns something like :

Creating list ...
Vector is full :
 -- first  object at 0x55d363e962c0
 -- second object at 0x55d363e962c1
 -- third  object at 0x55d363e962c2
End of program, dealocating vector ...
Destructing Object at 0x55d363e962c0
Destructing Object at 0x55d363e962c1
Destructing Object at 0x55d363e962c2