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std::default_delete

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< cpp‎ | memory
Revision as of 02:52, 25 April 2013 by P12 (Talk | contribs)

 
 
 
 
std::default_delete
 

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<td>
Defined in header <memory>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td >
template< class T > struct default_delete
</td>

<td > (1) </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
template< class T > struct default_delete<T[]>
</td>

<td > (2) </td> <td > (since C++11) </td> </tr> Template:ddcl list end

std::default_delete is the default destruction policy used by std::unique_ptr when no deleter is specified.

1) The non-specialized default_delete uses delete to deallocate memory for a single object.

2) A partial specialization for array types that uses delete[] is also provided.

Contents

Member functions

(constructor)
memconstructs a default_delete object
(public member function)
operator()
deletes the object or array
(public member function)

std::default_delete::default_delete

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<td >
constexpr default_delete = default;
</td>

<td > (1) </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
template <class U>
default_delete( const default_delete<U>& d );
</td>

<td > (2) </td> <td > (since C++11) </td> </tr> Template:ddcl list end

1) Constructs a std::default_delete object.
2) Constructs a std::default_delete object from another std::default_delete object. This constructor will only participate in overload resolution if U* is implicitly convertible to T*.

Parameters

d - a deleter to copy from

Exceptions

noexcept specification:  
noexcept
  

std::default_delete::operator()

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<td >
void operator()(T *ptr) const;
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<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> Template:ddcl list end

Calls either delete or delete[] on ptr.

Parameters

ptr - an object or array to delete

Exceptions

No exception guarantees.

Example

#include <memory>
#include <vector>
#include <algorithm>
 
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>());
}


See also

Template:cpp/memory/dcl list unique ptr