C++ set - empty() Function

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

Time Complexity

Constant i.e, Θ(1).

Example:

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

#include <iostream>
#include <set>
using namespace std;
 
int main (){
  set<int> MySet;

  cout<<boolalpha;

  cout<<"Is the Set empty?: "<<MySet.empty()<<"\n";

  cout<<"Add elements in the Set.\n";
  MySet.insert(10);
  MySet.insert(20);
  MySet.insert(30);

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

The output of the above code will be:

Is the Set empty?: true
Add elements in the Set.
Now, Is the Set empty?: false

❮ C++ <set> Library