std::unique_ptr in c++ | C++ 11

std::unique_ptr :

C++11 introduces std::unique_ptr, defined in the header .

It is a container for a raw pointer. A unique_ptr explicitly prevents copying of its contained pointer (as would happen with normal assignment), but the std::move function can be used to transfer ownership of the contained pointer to another unique_ptr.

Reason for it won’t allow copy :

A unique_ptr cannot be copied because its copy constructor and assignment operators are explicitly deleted.

std::unique_ptr p1(new int(5));

std::unique_ptr p2 = p1; //Compile error.

std::unique_ptr p3 = std::move(p1); //Transfers ownership. p3 now owns the memory and p1 is set to nullptr.

p3.reset(); //Deletes the memory.

p1.reset(); //Does nothing.



Complate Example: 

// C++ program to illustrate the use of unique_ptr #include #include using namespace std; class A { public:     void show()     {         cout<<"A::show()"<     } }; int main() {     unique_ptr p1 (new A);     p1 -> show();     // returns the memory address of p1     cout << p1.get() << endl;     // transfers ownership to p2     unique_ptr p2 = move(p1);     p2 -> show();     cout << p1.get() << endl;     cout << p2.get() << endl;     // transfers ownership to p3     unique_ptr p3 = move (p2);     p3->show();     cout << p1.get() << endl;     cout << p2.get() << endl;     cout << p3.get() << endl;     return 0; } Output:

A::show()
0x1c4ac20
A::show()
0          // NULL
0x1c4ac20
A::show()
0          // NULL
0          // NULL
0x1c4ac20