计算std :: vector的复制和移动数量

Question

I have a program written in C++11 and I would like to count the number of move and copy (construction and assignment) of std::vector<double> objects. Is there a way to do that?

Best regards

Answer 1

No . The implementation of std::vector<> provides no way for that. Neither does any compiler I know of.

As mentioned in the comments, you could create your own counting replacement and use that instead. Ie

struct counting_vector_double
: std::vector<double>
{
  static size_t count_copy_ctor;
  static size_t count_move_ctor;

  counting_vector_double(counting_vector_double const&other)
  : std::vector<double>(other)
  { count_copy_ctor++; }

  // etc
};

// in .cc file:
size_t counting_vector_double::count_copy_ctor = 0;
size_t counting_vector_double::count_move_ctor = 0;

(in a multi-threaded situation use atomic counters.) To implement this, you may use a typedef or using directive, like

#ifdef CountingMoveCopy
using vector_double = counting_vector_double;
#else
using vector_double = std::vector<double>;
#endif

and use vector_double in your code.

Answer 2

This answer consider that the OP needs to count the how many times the items of the vector are copied, moved, constructed.. etc) not the vector itself.

---

Although it is not a direct answer to your question, you may be interested in this answer.

Make a small wrapper class around double:

struct double_wrapper{
    double_wrapper()=delete;
    double_wrapper(const double value):value_(value){
        ++constructions_count;
    }
    double_wrapper(const double_wrapper& other){
        value_=other.value_;
        ++copies_count;
    }
    double_wrapper(double_wrapper&& other){
        value_=other.value_;
        //invalidate it in someway.. maybe set it to 0 (not important anyway)
        ++moves_count;
    }
    operator double() const {
         return value_;
    }

    double value_;
    static unsigned int copies_count;
    static unsigned int constructions_count;
    static unsigned int moves_count;
}

// in .cpp
unsigned int double_wrapper::copies_count=0;
unsigned int double_wrapper::constructions_count=0;
unsigned int double_wrapper::moves_count=0;

Finally, you have to edit the vector type (you may short it to Debug Mode with some #ifdef ):

std::vector<double_wrapper> v1;

Note: not tested.

Answer 3

规避该限制的一种可能方法是，使Vector类继承一个std :: vector，然后重载move和copy运算符以增加内部计数器。