unordered-map-functions.md

title	description	ms.date	f1_keywords	helpviewer_keywords
<unordered_map> functions	Learn more about: <unordered_map> functions	11/04/2016	unordered_map/std::swap unordered_map/std::swap (unordered_map) unordered_map/std::swap (unordered_multimap)	std::swap (unordered_map/multimap)

<unordered_map> functions

swap (unordered_map)
swap (unordered_multimap)

swap (unordered_map)

Swaps the contents of two containers.

template <class Key, class Ty, class Hash, class Pred, class Alloc>
void swap(
    unordered_map <Key, Ty, Hash, Pred, Alloc>& left,
    unordered_map <Key, Ty, Hash, Pred, Alloc>& right);

Parameters

Key
The key type.

Ty
The mapped type.

Hash
The hash function object type.

Pred
The equality comparison function object type.

Alloc
The allocator class.

left
The first container to swap.

right
The second container to swap.

Remarks

The template function executes left.unordered_map::swap(right).

Example

// std__unordered_map__u_m_swap.cpp
// compile with: /EHsc
#include <unordered_map>
#include <iostream>

typedef std::unordered_map<char, int> Mymap;
int main()
    {
    Mymap c1;

    c1.insert(Mymap::value_type('a', 1));
    c1.insert(Mymap::value_type('b', 2));
    c1.insert(Mymap::value_type('c', 3));

// display contents " [c 3] [b 2] [a 1]"
    for (Mymap::const_iterator it = c1.begin();
        it != c1.end(); ++it)
        std::cout << " [" << it->first << ", " << it->second << "]";
    std::cout << std::endl;

    Mymap c2;

    c2.insert(Mymap::value_type('d', 4));
    c2.insert(Mymap::value_type('e', 5));
    c2.insert(Mymap::value_type('f', 6));

    c1.swap(c2);

// display contents " [f 6] [e 5] [d 4]"
    for (Mymap::const_iterator it = c1.begin();
        it != c1.end(); ++it)
        std::cout << " [" << it->first << ", " << it->second << "]";
    std::cout << std::endl;

    swap(c1, c2);

// display contents " [c 3] [b 2] [a 1]"
    for (Mymap::const_iterator it = c1.begin();
        it != c1.end(); ++it)
        std::cout << " [" << it->first << ", " << it->second << "]";
    std::cout << std::endl;

    return (0);
    }

[c, 3] [b, 2] [a, 1]
[f, 6] [e, 5] [d, 4]
[c, 3] [b, 2] [a, 1]

swap (unordered_multimap)

Swaps the contents of two containers.

template <class Key, class Ty, class Hash, class Pred, class Alloc>
void swap(
    unordered_multimap <Key, Ty, Hash, Pred, Alloc>& left,
    unordered_multimap <Key, Ty, Hash, Pred, Alloc>& right);

Parameters

Key
The key type.

Ty
The mapped type.

Hash
The hash function object type.

Pred
The equality comparison function object type.

Alloc
The allocator class.

left
The first container to swap.

right
The second container to swap.

Remarks

The template function executes left.unordered_multimap::swap(right).

Example

// std__unordered_map__u_mm_swap.cpp
// compile with: /EHsc
#include <unordered_map>
#include <iostream>

typedef std::unordered_multimap<char, int> Mymap;
int main()
{
    Mymap c1;

    c1.insert(Mymap::value_type('a', 1));
    c1.insert(Mymap::value_type('b', 2));
    c1.insert(Mymap::value_type('c', 3));

    // display contents " [c 3] [b 2] [a 1]"
    for (Mymap::const_iterator it = c1.begin();
        it != c1.end(); ++it)
        std::cout << " [" << it->first << ", " << it->second << "]";
    std::cout << std::endl;

    Mymap c2;

    c2.insert(Mymap::value_type('d', 4));
    c2.insert(Mymap::value_type('e', 5));
    c2.insert(Mymap::value_type('f', 6));

    c1.swap(c2);

    // display contents " [f 6] [e 5] [d 4]"
    for (Mymap::const_iterator it = c1.begin();
        it != c1.end(); ++it)
        std::cout << " [" << it->first << ", " << it->second << "]";
    std::cout << std::endl;

    swap(c1, c2);

    // display contents " [c 3] [b 2] [a 1]"
    for (Mymap::const_iterator it = c1.begin();
        it != c1.end(); ++it)
        std::cout << " [" << it->first << ", " << it->second << "]";
    std::cout << std::endl;

    return (0);
}

[c, 3] [b, 2] [a, 1]
[f, 6] [e, 5] [d, 4]
[c, 3] [b, 2] [a, 1]

See also

<unordered_map>