C++ .empty()

The .empty() method checks whether an unordered_set has no elements. It returns true if the container is empty (i.e., its size is 0) and false otherwise.

Syntax

unordered_set_name.empty()

Parameters:

This method does not take any parameters.

Return value:

Returns true if the unordered_set is empty and false otherwise.

Example

The following example demonstrates how to use the .empty() method with std::unordered_set in C++:

#include <iostream>
#include <unordered_set>

int main() {
  std::unordered_set<int> numbers;

  if (numbers.empty()) {
    std::cout << "Unordered set is empty\n";
  } else {
    std::cout << "Unordered set has elements\n";
  }

  numbers.insert(10);
  numbers.insert(20);
  numbers.insert(30);

  if (numbers.empty()) {
    std::cout << "Unordered set is empty\n";
  } else {
    std::cout << "Unordered set has elements\n";
  }

  return 0;
}

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The output of the above code is:

Unordered set is empty
Unordered set has elements

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Codebyte Example

In this example, the .empty() method is used to control a loop that processes and removes elements from an unordered_set until it becomes empty:

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