C++ map - empty() Function

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

Time Complexity

Constant i.e, Θ(1).

Example:

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

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

  cout<<boolalpha;

  cout<<"Is the Map empty?: "<<MyMap.empty()<<"\n";

  cout<<"Add key/element pairs in the Map:\n";

  MyMap[101] = "John";
  MyMap[102] = "Marry";
  MyMap[103] = "Kim";

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

The output of the above code will be:

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

❮ C++ <map> Library