std::stack swap()

since C++11

// Non const version only
void swap( queue& other ) noexcept(/* see below*/);

Exchanges the contents of the container adaptor with those of other.

note

Effectively does:

using std::swap;
swap(c, other.c);

Parameters

• other - container adaptor to exchange the contents with

Return valued

(none)

Exceptions

since C++17

noexcept specification:

noexcept(std::is_nothrow_swappable_v<Container>)

since C++11

noexcept specification:

noexcept(noexcept(swap(c, other.c)))

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.

Complexity

Equivalent to that of swap of the underlying container.

note

For standard containers the complexity is guaranteed to be:

• Linear in the size of the container - O(size()), for std::array.
• Constant - O(1), for all other containers.

Notes

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

Example

Main.cpp

#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