There are such cases when we need to store pointers in the container. The examples are: storing polymorphic data in containers, forcing fast copy of data in containers, and strict exception requirements for operations with data in containers. In such cases, C++ programmer has the following choices:

• Store pointers in containers and take care of their destructions using delete:

#include <set>
#include <algorithm>
#include <cassert>

template <class T>
struct ptr_cmp {
    template <class T1>
    bool operator()(const T1& v1, const T1& v2) const {
        return operator ()(*v1, *v2);
    }

    bool operator()(const T& v1, const T& v2) const {
        return std::less<T>()(v1, v2);
    }
};

void example1() {
    std::set<int*, ptr_cmp<int> > s;
    s.insert(new int(1));
    s.insert(new int(0));

    // ...
   ...