Question

I am getting a warning in my code:

warning: taking address of temporary

I have seen similar questions, but they do not answer my specific problem.

Here is what my code is doing:

vector<A*>* ex_A;

ex_A->push_back( &A());  //I get this warning taking address of temporary

Is this undefined behavior?

I did have this before, which was fine, but i didn’t want to worry about deleting memory from the heap.

vector<A*>* ex_A;

ex_A->push_back( new A());

Could some one explain to me what the warning means?

Answer 1

&A() is creating a temporary object which gets destructed on exit of the full expression automagically, while new A() creates a new object on the heap which will live until you manually destroy it using delete.

I should add that if you store objects allocated with new in your vector<A*> and the vector gets destructed, the objects stored inside will not get deleted automatically, thus you will have a memory leak. You can verify this by using valgrind --leak-check=full my_compiled_program on your program, which generally is a good idea.