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multimap swap() function in C++ STL
  • Last Updated : 18 Nov, 2020
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The multimap::swap() is a built-in function in C++ STL which swaps two multimap container. The contents of multimap1 are in multimap2 and contents of multimap2 are in multimap1 after swap() function is called.

Syntax:

multimap1_name.swap(multimap2_name)

Parameters: This function accepts one parameter which is to be swapped with the multimap1_name,

Return Value: The function does not returns anything.




// C++ function for illustration
// multimap::swap() function
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
  
    // initialize container
    multimap<int, int> mp1, mp2;
  
    // insert elements in random order
    mp1.insert({ 2, 30 });
    mp1.insert({ 1, 40 });
  
    mp2.insert({ 10, 60 });
    mp2.insert({ 9, 20 });
  
    cout << "\nThe multimap1 before applying swap() is : \n";
    cout << "KEY\tELEMENT\n";
    for (auto itr = mp1.begin(); itr != mp1.end(); ++itr) {
        cout << itr->first
             << '\t' << itr->second << '\n';
    }
  
    cout << "\nThe multimap2 before applying swap() is : \n";
    cout << "KEY\tELEMENT\n";
    for (auto itr = mp2.begin(); itr != mp2.end(); ++itr) {
        cout << itr->first
             << '\t' << itr->second << '\n';
    }
  
    // performs swap operation of two multimap
    mp1.swap(mp2);
  
    cout << "\nThe multimap1 after applying swap() is : \n";
    cout << "KEY\tELEMENT\n";
    for (auto itr = mp1.begin(); itr != mp1.end(); ++itr) {
        cout << itr->first
             << '\t' << itr->second << '\n';
    }
  
    cout << "\nThe multimap2 after applying swap() is : \n";
    cout << "KEY\tELEMENT\n";
    for (auto itr = mp2.begin(); itr != mp2.end(); ++itr) {
        cout << itr->first
             << '\t' << itr->second << '\n';
    }
  
    return 0;
}
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