NAME¶

std::vector::swap - std::vector::swap

Synopsis¶

Defined in header <vector>
static void swap( reference x, reference y ); (until C++20)
constexpr static void swap( reference x, reference y ); (since C++20)

Swaps the contents of x and y as if by bool b = x; x = y; y = b;.

Parameters¶

x - std::vector<bool>::reference value to swap with y
y - std::vector<bool>::reference value to swap with x

Return value¶

(none)

Complexity¶

Constant.

Example¶

// Run this code

#include <iostream>
#include <vector>

void println(std::string_view fmt, std::vector<bool> const& vb = {})
{
for (std::cout << fmt; bool const e : vb)
std::cout << e << ' ';
std::cout << '\n';
}

int main()
{
println("swap elements of the same vector:");
std::vector<bool> x{1, 0};
println("before swap, x: ", x);
x.swap(x[0], x[1]); // same as std::vector<bool>::swap(x[0], x[1]);
println("after swap, x: ", x);

println("swap elements of two different vectors:");
std::vector<bool> y{0, 0, 1};
println("before swap, x: ", x);
println("before swap, y: ", y);
y.swap(x[0], y[2]); // same as std::vector<bool>::swap(x[0], y[2]);
println("after swap, x: ", x);
println("after swap, y: ", y);
}

Output:¶

swap elements of the same vector:
before swap, x: 1 0
after swap, x: 0 1
swap elements of two different vectors:
before swap, x: 0 1
before swap, y: 0 0 1
after swap, x: 1 1
after swap, y: 0 0 0

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 814 C++98 the description of this member function was added
missing

See also¶

reference proxy class representing a reference to a single bool
(class)
swap swaps the contents
(public member function of std::vector<T,Allocator>)
std::swap(std::vector) specializes the std::swap algorithm
(function template)