Guess the output for C++11?
#include<iostream>
class ArrayNotFound
{
private:
int id;
public:
ArrayNotFound(int a)
{
std::cout<<"ArrayNotFound
constructor called: "<<a<<std::endl;
id=a;
}
~ArrayNotFound()
{
std::cout<<"ArrayNotFound
destructor called: "<<id<<std::endl;
}
};
int main()
{
/* C++11 - Assume move constructor is supported
*/
ArrayNotFound l_obj = ArrayNotFound(1);
const ArrayNotFound &l_ref_obj =
ArrayNotFound(2);
ArrayNotFound &&rvalue_ref_obj =
ArrayNotFound(3);
ArrayNotFound(4);
ArrayNotFound l_obj3 = ArrayNotFound(5);
ArrayNotFound l_obj2(6);
return 0;
}
Output:
ArrayNotFound
constructor called: 1
ArrayNotFound
constructor called: 2
ArrayNotFound
constructor called: 3
ArrayNotFound
constructor called: 4
ArrayNotFound
destructor called: 4
ArrayNotFound
constructor called: 5
ArrayNotFound
constructor called: 6
ArrayNotFound
destructor called: 6
ArrayNotFound
destructor called: 5
ArrayNotFound
destructor called: 3
ArrayNotFound
destructor called: 2
ArrayNotFound
destructor called: 1
EXPLANATION:
Usually destructor will be called immediately for temporary objects
soon after the construction.
As said above, destructor for following declaration method will
be called immediately
ArrayNotFound(4);
But In the following objects creation method, even though temporary
objects is used to create objects, destructor will not be called immediately. This
is because of move semantics concept in c++. Temporary objects created will be moved
instead of copying and destroying the temporary object.
ArrayNotFound l_obj =
ArrayNotFound(1);
const ArrayNotFound
&l_ref_obj = ArrayNotFound(2);
ArrayNotFound
&&rvalue_ref_obj = ArrayNotFound(3);
ArrayNotFound l_obj3
= ArrayNotFound(5);
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