The creator of c++, Bjarne Stroustrup, says that he deliberately did not emphasize on the use of a Garbage Collector for C++ as he feels that Garbage shouldn't exist at all in the first place. So you are responsible for allocation/deallocation of pointers. Though nowadays, you can just use smart_pointers and containers and leave all the tasks to them.
Also, if you are in dire need of a garbage collector, external libraries are available for the same. You can also use C++/CLI, a microsoft version of C++, as it has its own Garbage Collector like C#.