C++ <stack> - empty() Function

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

Syntax

C++98
C++11

bool empty() const;

bool empty() const;

Parameters

No parameter is required.

Return Value

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

Time Complexity

Constant i.e, Θ(1).

Example:

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

#include <iostream>
#include <stack>
using namespace std;
 
int main (){
  stack<int> MyStack;

  cout<<boolalpha;

  cout<<"Is the Stack empty?: "<<MyStack.empty()<<"\n";

  cout<<"Add elements in the Stack.\n";
  MyStack.push(10);
  MyStack.push(20);
  MyStack.push(30);

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

The output of the above code will be:

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

❮ C++ <stack> Library