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multimap::find

Returns an iterator that refers to the first location of an element in a multimap that has a key equivalent to a specified key.

iterator find(const Key& key);

const_iterator find(const Key& key) const;

key

The key value to be matched by the sort key of an element from the multimap being searched.

An iterator that refers to the location of an element with a specified key, or the location succeeding the last element in the multimap (multimap::end()) if no match is found for the key.

The member function returns an iterator that refers to an element in the multimap whose sort key is equivalent to the argument key under a binary predicate that induces an ordering based on a less than comparability relation.

If the return value of find is assigned to a const_iterator, the multimap object cannot be modified. If the return value of find is assigned to an iterator, the multimap object can be modified.

// compile with: /EHsc /W4 /MTd
#include <map>
#include <iostream>
#include <vector>
#include <string>
#include <utility>  // make_pair()

using namespace std;

template <typename A, typename B> void print_elem(const pair<A, B>& p) {
    cout << "(" << p.first << ", " << p.second << ") ";
}

template <typename T> void print_collection(const T& t) {
    cout << t.size() << " elements: ";

    for (const auto& p : t) {
        print_elem(p);
    }
    cout << endl;
}

template <typename C, class T> void findit(const C& c, T val) {
    cout << "Trying find() on value " << val << endl;
    auto result = c.find(val);
    if (result != c.end()) {
        cout << "Element found: "; print_elem(*result); cout << endl;
    } else {
        cout << "Element not found." << endl;
    }
}

int main()
{
    multimap<int, string> m1({ { 40, "Zr" }, { 45, "Rh" } });
    cout << "The starting multimap m1 is (key, value):" << endl;
    print_collection(m1);

    vector<pair<int, string>> v;
    v.push_back(make_pair(43, "Tc"));
    v.push_back(make_pair(41, "Nb"));
    v.push_back(make_pair(46, "Pd"));
    v.push_back(make_pair(42, "Mo"));
    v.push_back(make_pair(44, "Ru"));
    v.push_back(make_pair(44, "Ru")); // attempt a duplicate

    cout << "Inserting the following vector data into m1:" << endl;
    print_collection(v);

    m1.insert(v.begin(), v.end());

    cout << "The modified multimap m1 is (key, value):" << endl;
    print_collection(m1);
    cout << endl;
    findit(m1, 45);
    findit(m1, 6);
}

The starting multimap m1 is (key, value):
2 elements: (40, Zr) (45, Rh)
Inserting the following vector data into m1:
6 elements: (43, Tc) (41, Nb) (46, Pd) (42, Mo) (44, Ru) (44, Ru)
The modified multimap m1 is (key, value):
8 elements: (40, Zr) (41, Nb) (42, Mo) (43, Tc) (44, Ru) (44, Ru) (45, Rh) (46, Pd)

Trying find() on value 45
Element found: (45, Rh)
Trying find() on value 6
Element not found.

Header: <map>

Namespace: std

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