std::swap(std::basic_string)

From cppreference.com
< cpp‎ | string‎ | basic string
 
 
 
std::basic_string
Member functions
Element access
Iterators
Capacity
Operations
Search
Constants
Deduction guides (C++17)
Non-member functions
swap(std::basic_string)
I/O
Comparison
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Numeric conversion
(C++11)(C++11)(C++11)
(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)
(C++11)
Helper classes
 
Defined in header <string>
template< class CharT, class Traits, class Alloc >

void swap( std::basic_string<CharT, Traits, Alloc>& lhs,

           std::basic_string<CharT, Traits, Alloc>& rhs );
(until C++17)
template< class CharT, class Traits, class Alloc >

void swap( std::basic_string<CharT, Traits, Alloc>& lhs,

           std::basic_string<CharT, Traits, Alloc>& rhs ) noexcept(/* see below */);
(since C++17)
(until C++20)
template< class CharT, class Traits, class Alloc >

constexpr void
    swap( std::basic_string<CharT, Traits, Alloc>& lhs,

          std::basic_string<CharT, Traits, Alloc>& rhs ) noexcept(/* see below */);
(since C++20)

Specializes the std::swap algorithm for std::basic_string. Swaps the contents of lhs and rhs.

Equivalent to lhs.swap(rhs).

Parameters

lhs, rhs - strings whose contents to swap

Return value

(none)

Complexity

Constant.

Exceptions

noexcept specification:  
noexcept(noexcept(lhs.swap(rhs)))
(since C++17)

Example

#include <iostream>
#include <string>
 
int main()
{
    std::string a = "AAA";
    std::string b = "BBBB";
 
    std::cout << "Before swap:\n"
                 "a = " << a << "\n"
                 "b = " << b << "\n\n";
 
    std::swap(a, b);
 
    std::cout << "After swap:\n"
                 "a = " << a << "\n"
                 "b = " << b << '\n';
}

Output:

Before swap:
a = AAA
b = BBBB
 
After swap:
a = BBBB
b = AAA

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2064 C++11 non-member swap was noexcept and inconsistent with member swap noexcept removed

See also

swaps the contents
(public member function)