Skip to main content

std::auto_ptr in c++

Automatic Pointer [deprecated]
Note: This class template is deprecated as of C++11 and completely removed in c++ 17. unique_ptr is a new facility with a similar functionality, but with improved security (no fake copy assignments), added features (deleters) and support for arrays.


auto_ptr objects have the uniqueness of taking ownership of the pointers allotted to them: An auto_ptr object that has ownership over one element is in charge of destroying the element it points to and to deallocate the memory allocated to it when itself is destroyed. The destructor does this by invoking operator delete automatically.

Hence, no two auto_ptr objects should own the same element, since together would try to destruct them at some point. When an assignment operation takes place between two auto_ptr objects, ownership is transferred, which means that the object losing ownership is set to no longer point to the element (it is set to the null pointer).




#include
void memory_leak() 
{
std::auto_ptr ptrClassA_1(new ClassA);
        std::auto_ptr ptrClassA_2 = ptrClassA_1; // ownership gets tranfered from ptrClassA_1 to ptrClassA_2
...
}

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