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std::swap

From cppreference.com
< cpp‎ | algorithm
 
 
Algorithm library
Execution policies (C++17)
Non-modifying sequence operations
(C++11)(C++11)(C++11)
(C++17)
Modifying sequence operations
Operations on uninitialized storage
Partitioning operations
Sorting operations
(C++11)
Binary search operations
Set operations (on sorted ranges)
Heap operations
(C++11)
Minimum/maximum operations
(C++11)
(C++17)

Permutations
Numeric operations
C library
 
Defined in header <algorithm>
Defined in header <utility>
(until C++11)
(since C++11)
template< class T >
void swap( T& a, T& b );
(1)
template< class T2, size_t N >
void swap( T2 (&a)[N], T2 (&b)[N]);
(2) (since C++11)

Exchanges the given values.

1) Swaps the values a and b. This overload does not participate in overload resolution unless std::is_move_constructible_v<T> && std::is_move_assignable_v<T> is true. (since C++17)
2) Swaps the arrays a and b. In effect calls std::swap_ranges(a, a+N, b). This overload does not participate in overload resolution unless std::is_swappable_v<T> is true. (since C++17)

Contents

[edit] 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.

[edit] Return value

(none)

[edit] Exceptions

1)
(none) (until C++11)
noexcept specification:  
noexcept(

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

)
(since C++11)
2)
noexcept specification:  
noexcept(noexcept(swap(*a, *b)))
(until C++17)
noexcept specification:  
noexcept(std::is_nothrow_swappable_v<T>)
(since C++17)

[edit] Complexity

1) Constant
2) Linear in N

[edit] Specializations

std::swap may be specialized in namespace std for user-defined types, but such specializations are not found by ADL (the namespace std is not the associated namespace for the user-defined type). The expected way to make a user-defined type swappable is to provide a non-member function swap in the same namespace as the type: see Swappable for details.

The following overloads are already provided by the standard library:

specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap() algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap() algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specialization of std::swap for unique_lock
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
specializes the std::swap algorithm
(function) [edit]
specializes the std::swap algorithm
(function) [edit]
specializes the std::swap algorithm
(function) [edit]
swaps two paths
(function) [edit]

[edit] Example

#include <algorithm>
#include <iostream>
 
int main()
{
   int a = 5, b = 3;
 
   // before
   std::cout << a << ' ' << b << '\n';
 
   std::swap(a,b);
 
   // after
   std::cout << a << ' ' << b << '\n';
}

Output:

5 3
3 5

[edit] See also

swaps the elements pointed to by two iterators
(function template) [edit]
swaps two ranges of elements
(function template) [edit]