C++ Map Library - swap() Function

---

---

Description

The C++ function std::multimap::swap() exchanges the content of multimap with contents of mutlimap x.

Declaration

Following is the declaration for std::multimap::swap() function form std::map header.

C++98

template <class Key, class T, class Compare, class Alloc>
   void swap (multimap<Key,T,Compare,Alloc>& first, 
      multimap<Key,T,Compare,Alloc>& second);

Parameters

• first − First multimap object.

• second − Second multimap object of same type.

Return value

None

Exceptions

No effect on container if exception is thrown.

Time complexity

Constant i.e. O(1)

Example

The following example shows the usage of std::multimap::swap() function.

#include <iostream>
#include <map>

using namespace std;

int main(void) {
   /* Multimap with duplicates */
   multimap<char, int> m1 {
            {'a', 1},
            {'a', 2},
            {'b', 3},
            {'c', 4},
            {'d', 5}
         };

   multimap<char, int> m2;

   swap(m1, m2);

   cout << "Multimap contains following elements:" << endl;

   for (auto it = m2.begin(); it != m2.end(); ++it)
      cout << it->first << " = " << it->second << endl;

   return 0;
}

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

Multimap contains following elements:
a = 1
a = 2
b = 3
c = 4
d = 5