multimap insert() in C++ STL

The multimap::insert is a built-in function in C++ STL which is used to insert elements in the multimap container.

1. Syntax:

   iterator multimap_name.insert({key, element})
   

   Parameters: The function accepts a pair that consists of a key and element which is to be inserted into the multimap container.

   Return Value: The function returns an iterator pointing to the new element in the container.

   // C++ program to illustrate // multimap::insert({key, element}) #include <bits/stdc++.h> using namespace std;    int main() {        // initialize container     multimap<int, int> mp;        // insert elements in random order     mp.insert({ 2, 30 });     mp.insert({ 1, 40 });     mp.insert({ 3, 60 });     mp.insert({ 2, 20 });     mp.insert({ 5, 50 });        // prints the elements     cout << "KEY ELEMENT ";     for (auto itr = mp.begin(); itr != mp.end(); ++itr) {         cout << itr->first              << ' ' << itr->second << ' ';     }     return 0; }

   Output:

   KEY    ELEMENT
   1    40
   2    30
   2    20
   3    60
   5    50
   

2. Syntax:

   iterator multimap_name.insert(iterator position, {key, element})
   

   Parameters: The function accepts two parameters which is described below:

   
   
   
   • {key, element}: this specifies a pair that consists of a key and element which is to be inserted into the multimap container.
   • position: this does not specify the position where the insertion is to be done, it only points a position from where the searching operation for insertion is to be started. The insertion is done according to the order which is followed by the multimap container.

   Return Value: The function returns an iterator pointing to the new element in the container.

   // C++ program to illustrate // multimap::insert({key, element}) #include <bits/stdc++.h> using namespace std;    int main() {        // initialize container     multimap<int, int> mp;        // insert elements in random order     mp.insert({ 2, 30 });     mp.insert({ 1, 40 });        auto it = mp.find(2);        // inserts {3, 6} starting the search from     // position where 2 is present     mp.insert(it, { 3, 60 });        // prints the elements     cout << "KEY ELEMENT ";     for (auto itr = mp.begin(); itr != mp.end(); ++itr) {         cout << itr->first              << ' ' << itr->second << ' ';     }     return 0; }

   Output:

   KEY    ELEMENT
   1    40
   2    30
   3    60
   

3. Syntax:

   iterator multimap_name.insert(iterator position1, iterator position2)
   

   Parameters: The function accepts two parameters position1 and position2 which specifies the range of elements. All the elements in the range [position1, last) are inserted in the multimap container.

   Return Value: The function returns an iterator pointing to the new element in the container.

   // C++ program to illustrate // multimap::insert({key, element}) #include <bits/stdc++.h> using namespace std;    int main() {        // initialize container     multimap<int, int> mp, mp1;        // insert elements in random order     mp.insert({ 2, 30 });     mp.insert({ 1, 40 });        // inserts all elements in range [begin, end)     // in mp1     mp1.insert(mp.begin(), mp.end());        // prints the elements     cout << "Elements in mp1 are ";     cout << "KEY ELEMENT ";     for (auto itr = mp1.begin(); itr != mp1.end(); ++itr) {         cout << itr->first              << ' ' << itr->second << ' ';     }     return 0; }

   Output:

   Elements in mp1 are
   KEY    ELEMENT
   1    40
   2    30