c++ - how to count not deleted instances in array of instances? -

i have array of instances in code, :

class squad : public isquad {     public:         squad(void);         squad(squad const & src);         virtual ~squad(void);          int             getcount(void) const;         int             push(ispacemarine*);         ispacemarine*   getunit(int) const;          ispacemarine**              getunits(void) const;         int                         getcapacity(void) const;          squad &     operator=(squad const & rhs);          private:         ispacemarine    **_units; // here array of instances         int const       _squadcapacity;  }; 

initialized in constructor

squad::squad(void) : _units(new ispacemarine*[64]), _squadcapacity(64) {     return; } 

first, the way ?

if yes, try count number of valid instances in array (not null, not deleted) don't know how check if _units[20] deleted example.

how can ?

he current way do:

int                         squad::getcount(void) const {     int     count = 0;     while (this->_units[count] != null && count < this->_squadcapacity)         count++;     return count; } 

    ispacemarine    **_units; // here array of instances     int const       _squadcapacity; 

- first, the way ?

no, not way go , neatly shows why std containers , smart pointers big improvement.

with smart pointers express , deal ownership automatically.

i impression squad manages spacemarines, in case should use std::unique_ptr. squad like

class squad : public isquad {   public:     size_t             getcount() const;     void             push(ispacemarine&&);     using spacemarineiterator = std::vector<std::unique_ptr<spacemarine>>::iterator;     // typedef/using iterator appropriate.     spacemarineiterator getunit(int) const;     // ,     spacemarineiterator begin() const;     spacemarineiterator end() const;      size_t                         getcapacity() const;     // no need copy assign either.     //squad &     operator=(squad const & rhs);        private:     std::vector<std::unique_ptr<ispacemarine>> units;   // no need capacity.  }; 

now, if need different model ownership can std::shared_ptr , std::weak_ptr. model should make effort work std::unique_ptr though.

note: don't discard possibility of using

std::vector<spacemarine> units;