Skip to main content

Disallow the use of compiler generated functions

/* C++ 11 Update: Delete keyword */
class dog {
   public:
   dog(const dog& ) = delete; // Prevent copy constructor from being used.
                              // Useful when dog holds unsharable resource.
}

/* For C++ 03:
Solution:
 Declare them as private functions, but not define them.
 -- Members and friends get link-time error, others get compile-time error.
*/
class dog {
   private:
   dog& operator=(const dog& rhs);   
};
// Note: the same techniques can used to disallow any function from being used.



Question: Can we disallow destructor from being used? 
/* Solution */
class dog {
  public:
     void destroyMe() { delete this; }
     void dog(string message) { cout<
  private:
     ~dog() { cout<< m_name.m_str << " is destroyed.\n" << endl; }
};

 int main ()
{
  dog dog1("Dog Barks");
  dog1->destroyMe();  
}  

 // Error : Though we have invoke function to delete object through delete, but still when function goes out of scope destructor gets called and results in runtime error.

Solution: Create pointer on heap
int main ()
{
  dog* dog1 = new dog("Dog Barks");
  dog1->destroyMe();
}

Labels:

Comments

Post a Comment

Popular posts from this blog

Part1 : STL Algorithms (Non-Modifying sequence) in c++

Non-Modifying sequence operations : 1.  Non-modifying sequence operations:   _of (CPP 11) std::array all_of_elem = { 3,5,7,11,13,17,19,23 }; 1. if ( std::all_of ( all_of_elem.begin(),   all_of_elem.end() ,  [](int i) {return i % 2; } )) std::cout << "All the elements are odd numbers.\n"; std::array any_of_elem = { 0,1,-1,3,-3,5,-5 }; 2. if ( std::any_of ( any_of_elem.begin() ,  any_of_elem.end() ,  [](int i) {return i )) std::cout << "There are negative elements in the range.\n"; std::array foo = { 1,2,4,8,16,32,64,128 }; 3. if ( std::none_of ( foo.begin() ,  foo.end() ,  [](int i) {return i )) std::cout << "There are no negative elements in the range.\n"; 2.  Non-modifying sequence operations:   find       std::string myints[] = { "Hello", "Hi", "Bye", "ByeBye" }; std::vector myvector(myints, myints + 4); std::vector ::iterator it;...
Post a Comment
Read more

Structured Bindings

Returning multiple Values from function C++ 11 vs C++ 17 Returning compound objects Iterating over a compound collection Direct initialization Returning multiple Values from function C++ 11 vs C++ 17 :  C++ 11 (std::tie): std::tuple mytuple() {     char a = 'a';     int i = 123;     bool b = true;     return std::make_tuple(a, i, b);  // packing variable into tuple } To access return value using C++ 11, we would need something like: char a; int i; bool b; std::tie(a, i, b) = mytuple();  // unpacking tuple into variables Where the variables have to be defined before use and the types known in advance. C++ 17 : auto [a, i, b] = mytuple(); Returning compound objects :  This is the easy way to assign the individual parts of a compound type (such as a struct, pair etc) to different variables all in one go – and have the correct types automatically assigned. So let’s have a look at an ...
Post a Comment
Read more

Containers in c++

SEQUENTIAL CONTAINER Vector (Dynamic Array - Contiguous memory):  O(1): Vectors provide fast (constant time) element insertion and deletion at the end of the vector and Acess. O(n): Slow (linear time) insertion and deletion anywhere else. Insertion and deletion are slow because the operation must move all the elements “down” or “up” by one to make room for the new element or to fill the space left by the deleted element. Like arrays, vectors provide fast (constant time) access to any of their elements. List (Doubly Linked List - Not  Contiguous memory ): O(n): Lists provide slow (linear time) element lookup and access, O(1):  (constant time) insertion and deletion of elements once the relevant position has been found Deque (Doubly Ended Queue - Not Contiguous memory): O(1): (constant time) element access. Like a list, it provides fast (amortized constant time) insertion and deletion at both ends of the sequence. O(1):  (lin...
Post a Comment
Read more