std::default_delete

Since C++11

Header: <memory>

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.

# Declarations

template< class T > struct default_delete;

(since C++11)

template< class T > struct default_delete<T[]>;

(since C++11)

# Parameters

d: a deleter to copy from

# Notes

The converting constructor template of std::default_delete makes possible the implicit conversion from std::unique_ptr to std::unique_ptr.

# Example

#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[]>());
    } // OK: the destructor calls delete[]
 
    {
        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>());
}

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 2118	C++11	member functions of the array specializations rejected qualification conversions	accept

# See also

unique_ptr