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std::vector<bool,Allocator>::swap

From cppreference.com
 
 
 
 
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;.

Contents

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

#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 missing added

See also

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