C++ Unordered_multimap Library - insert() Function

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Description

The C++ function std::unordered_multimap::insert() extends unordered_multimap by inserting new element. 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

template <class P>
iterator insert(P&& val);

Parameters

val − Value to be inserted.

Return value

Returns an iterator pointing to the newly inserted element.

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},
            {'d', 4},
            };

   auto pos = umm.insert(move(pair<char, int>('e', 5)));

   cout << "After inserting new element iterator points to "
       << pos->first << " = " << pos->second << endl;

   return 0;
}

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

After inserting new element iterator points to e = 5