std::stack<T,Container>::empty

bool empty() const;
 (until C++20) 
[[nodiscard]] bool empty() const;
 (since C++20)

Checks if the underlying container has no elements. Equivalent to return c.empty();.

Parameters

(none)

Return value

true if the underlying container is empty, false otherwise.

Complexity

Constant.

Example

#include <algorithm>
#include <iostream>
#include <stack>
 
int main()
{
    std::cout << std::boolalpha;
 
    std::stack<int> stack;
 
    std::cout << "Initially, stack.empty(): " << stack.empty() << '\n';
 
    stack.push(42);
    std::cout << "After adding elements, stack.empty(): " << stack.empty() << '\n';
}

Output:

Initially, stack.empty(): true
After adding elements, stack.empty(): false

See also

returns the number of elements
(public member function)
(C++17)
 checks whether the container is empty
(function template)

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