std::swap

 

C++

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Symbols index

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Template:ddcl list begin <tr class="t-dsc-header">

<td>

Defined in header <algorithm>
Defined in header <utility>

</td>

<td></td>

<td>

(until C++11)
(since C++11)

</td>

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

<td >

template< class T >
void swap( T& a, T& b );

</td>

<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">

<td >

template< class T2, size_t N >
void swap( T2 (&a)[N], T2 (&b)[N]);

</td>

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

Exchanges the given values.

1) Swaps the values a and b.

2) Swaps the arrays a and b. In effect calls std::swap_ranges(a, a+N, b).

Parameters

a, b	-	the values to be swapped
Type requirements
- T must meet the requirements of MoveAssignable and MoveConstructible.
- T2 must meet the requirements of Swappable.

Return value

(none)

Exceptions

1)

noexcept specification:  

noexcept(noexcept(

    std::is_nothrow_move_constructible<T>::value &&
    std::is_nothrow_move_assignable<T>::value

))

2)

noexcept specification:  

noexcept(noexcept(swap(*a, *b)))

Complexity

1) Constant

2) Linear in N

Specializations

Both custom specializations and overloads of the std::swap algorithm are allowed, but the overloads are generally preferred since specializations of a function template aren't allowed for template classes. Library functions always use the user-provided overloads when swapping, if they are found by argument-dependent lookup (as per Template:concept concept).

The following overloads are already provided by the standard library:

Template:cpp/memory/shared ptr/dcl list swap2Template:cpp/memory/weak ptr/dcl list swap2Template:cpp/memory/unique ptr/dcl list swap2Template:cpp/string/basic string/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/container/dcl list swap2Template:cpp/io/basic fstream/dcl list swap2Template:cpp/io/basic fstream/dcl list swap2Template:cpp/io/basic fstream/dcl list swap2

std::swap(std::pair) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::tuple) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::function) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::valarray) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::basic_stringbuf) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::basic_istringstream) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::basic_ostringstream) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::basic_stringstream) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::basic_filebuf) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::basic_regex) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::match_results) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
swap(std::) ({{{1}}})	specializes the std::swap algorithm (function)
std::swap(std::unique_lock) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::promise) (C++11)	specializes the Template:cpp/ltf algorithm (function template)
std::swap(std::packaged_task) (C++11)	specializes the Template:cpp/ltf algorithm (function template)

See also

Template:cpp/algorithm/dcl list iter swapTemplate:cpp/algorithm/dcl list swap ranges