Simple C++ Shared Ptr

simple_shared_ptr.cpp

#include <iostream>

template <class T>
class SharedPtr {
 public:
  SharedPtr(T *rep = nullptr) : rep_(rep), count_ptr_(new int32_t(1)) {}

  SharedPtr(const SharedPtr &obj) : count_ptr_(obj.count_ptr_), rep_(obj.rep_) {
    increse();
  }

  SharedPtr &operator=(const SharedPtr &obj) {
    rep_ = obj.rep_;
    count_ptr_ = obj.count_ptr_;
    increse();

    return *this;
  }

  ~SharedPtr() {
    decrese();
    if (count() == 0) {
      delete count_ptr_;
      delete rep_;
    }
  }

  T *get() const { return rep_; }
  operator T *() const { return rep_; }

 private:
  T *rep_;

  int32_t *count_ptr_;
  int32_t count() const { return *count_ptr_; }
  void increse() { ++(*count_ptr_); }
  void decrese() { --(*count_ptr_); }
};

class A {
 public:
  A() { puts("New"); }
  ~A() { puts("Delete"); }
};

int main() {
  SharedPtr<A> b;

  {
    SharedPtr<A> a(new A);
    b = a;
    puts("OK");
  }
  puts("OK");
}