std::swap(std::basic_string)

 

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basic_string

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std::basic_string

Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (C++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (DR*) Modifiers basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)   basic_string::swap

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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) (constexpr 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

Run this code

#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

swap	swaps the contents (public member function)