C++ multimap - empty() Function

The C++ multimap::empty function is used to check whether the multimap is empty or not. It returns true if the size of the multimap is zero, else returns false.

Syntax

C++98
C++11

bool empty() const;

bool empty() const noexcept;

Parameters

No parameter is required.

Return Value

true if the size of the multimap is zero, else returns false.

Time Complexity

Constant i.e, Θ(1).

Example:

In the example below, the multimap::empty function is used to check whether the multimap is empty or not.

#include <iostream>
#include <map>
using namespace std;
 
int main (){
  multimap<string, string> MyMMap;

  cout<<boolalpha;

  cout<<"Is the Multimap empty?: "<<MyMMap.empty()<<"\n";

  cout<<"Add key/element pairs in the Multimap.\n";

  MyMMap.insert(pair<string, string>("USA", "New York"));
  MyMMap.insert(pair<string, string>("USA", "Washington"));  
  MyMMap.insert(pair<string, string>("CAN", "Toronto"));

  cout<<"Now, Is the Multimap empty?: "<<MyMMap.empty()<<"\n";
  return 0;
}

The output of the above code will be:

Is the Multimap empty?: true
Add key/element pairs in the Multimap.
Now, Is the Multimap empty?: false

❮ C++ <map> Library