NAME

std::stack::swap - std::stack::swap

Synopsis

void swap( stack& other ) noexcept(/* see below */); (since C++11)

Exchanges the contents of the container adaptor with those of other. Effectively
calls using std::swap; swap(c, other.c);

Parameters

other - container adaptor to exchange the contents with

Return value

(none)

Exceptions

noexcept specification:
noexcept(noexcept(swap(c, other.c))) (since C++11)
(until C++17)
In the expression above, the identifier swap is looked up in the same
manner as the one used by the C++17 std::is_nothrow_swappable trait.
noexcept specification: (since C++17)
noexcept(std::is_nothrow_swappable_v<Container>)

Complexity

Same as underlying container (typically constant).

Notes

Some implementations (e.g. libc++) provide the swap member function as an extension
to pre-C++11 modes.

Example

// Run this code

#include <iostream>
#include <stack>
#include <string>
#include <vector>

template <typename Stack>
void print(Stack stack /* pass by value */, int id)
{
std::cout << "s" << id << " [" << stack.size() << "]: ";
for (; !stack.empty(); stack.pop())
std::cout << stack.top() << ' ';
std::cout << (id > 1 ? "\n\n" : "\n");
}

int main()
{
std::vector<std::string>
v1{"1","2","3","4"},
v2{"Ɐ","B","Ɔ","D","Ǝ"};

std::stack s1{std::move(v1)};
std::stack s2{std::move(v2)};

print(s1, 1);
print(s2, 2);

s1.swap(s2);

print(s1, 1);
print(s2, 2);
}

Output:

s1 [4]: 4 3 2 1
s2 [5]: Ǝ D Ɔ B Ɐ

s1 [5]: Ǝ D Ɔ B Ɐ
s2 [4]: 4 3 2 1

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 2456 C++11 the noexcept specification is ill-formed made to work