NAME¶

std::swap(std::basic_string) - std::swap(std::basic_string)

Synopsis¶

Defined in header <string>
template< class CharT, class Traits, class Alloc >

void swap( std::basic_string<CharT, Traits, Alloc>& lhs, (until C++17)

std::basic_string<CharT, Traits, Alloc>& rhs );
template< class CharT, class Traits, class Alloc >

void swap( std::basic_string<CharT, Traits, Alloc>& lhs, (since C++17)
(constexpr since C++20)
std::basic_string<CharT, Traits, Alloc>& rhs )
noexcept(/* see below */);

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¶

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

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 noexcept removed
with member swap

See also¶

swap swaps the contents
(public member function)

Category:¶

* conditionally noexcept