C++ Unordered_multimap Library - insert() Function

Description

The C++ function std::unordered_multimap::insert() extends unordered_multimap by inserting new element from initializer list. This function increases container size by one.

Declaration

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

C++11

void insert(initializer_list<value_type> il);

Parameters

il − Initializer list.

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> umm = {
            {'a', 1},
            {'b', 2},
            {'c', 3},
            };

   umm.insert({{'d', 4}, {'e', 5}});

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

   for (auto it = umm.begin(); it != umm.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
e = 5
d = 4
c = 3
a = 1
b = 2