std::default_delete is the default destruction policy used by std::unique_ptr when no deleter is specified. Specializations of default_delete are empty classes on typical implementations, and used in the empty base class optimization .

Parameters

In any case, if U is an incomplete type, the program is ill-formed.

Parameters

[ edit ] Invoking over Incomplete Types

At the point in the code the operator ( ) is called, the type must be complete. In some implementations a static_assert is used to make sure this is the case. The reason for this requirement is that calling delete on an incomplete type is undefined behavior in C++ if the complete class type has a nontrivial destructor or a deallocation function, as the compiler has no way of knowing whether such functions exist and must be invoked.

[ edit ] Notes

#include <algorithm>
#include <memory>
#include <vector>
int main()
//  {
//      std::shared_ptr<int> shared_bad(new int[10]);
//  } // the destructor calls delete, undefined behavior
        std::shared_ptr<int> shared_good(new int[10], std::default_delete<int[]>());
    } // the destructor calls delete[], ok
        std::unique_ptr<int> ptr(new int(5));
    } // unique_ptr<int> uses default_delete<int>
        std::unique_ptr<int[]> ptr(new int[10]);
    } // unique_ptr<int[]> uses default_delete<int[]>
    // default_delete can be used anywhere a delete functor is needed
    std::vector<int*> v;
    for (int n = 0; n < 100; ++n)
        v.push_back(new int(n));
    std::for_each(v.begin(), v.end(), std::default_delete<int>());
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.