C++ Unordered_multimap Library - insert() Function

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Description

The C++ function std::unordered_multimap::insert() extends container by inserting new elements in the unordered_multimap.

Declaration

Following is the declaration for std::unordered_multimap::insert() function form std::unordered_map() header.

C++11

template <class InputIterator>
void insert(InputIterator first, InputIterator last);

Parameters

• first − Input iterator to the initial position in range.

• last − Input iterator to the final position in range.

Return value

None

Time complexity

Constant i.e. O(1) in average case.

Linear i.e. O(n) in worst case.

Example

The following example shows the usage of std::unordered_multimap::insert() function.

#include <iostream>
#include <unordered_map>

using namespace std;

int main(void) {
   unordered_multimap<char, int> umm1 = {
            {'a', 1},
            {'b', 2},
            {'c', 3},
            {'d', 4},
         {'e', 5},
            };
   unordered_multimap<char, int> umm2;

   umm2.insert(umm1.begin(), umm1.end());

   cout << "Unordered multimap contains following elements" << endl;

   for (auto it = umm2.begin(); it != umm2.end(); ++it)
      cout << it->first << " = " << it->second << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Unordered multimap contains following elements
d = 4
c = 3
b = 2
a = 1
e = 5