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Showing content from https://www.tutorialspoint.com/cpp_standard_library/cpp_array_empty.htm below:

C++ Array Empty Check

The C++ std::array::empty() function is used to check whether a array is empty. Since the std::array is a fixed size container, its size is known at compile time, and it cannot be dynamically resized. This function always return false for std::array because array is never empty unless it has zero size(which is rare).

Following is the syntax for std::array::empty() function.

constexpr bool empty() noexcept;

This does not accepts any parameter.

It returns a bool value indicating whether the array is empty or not.

This function never throws exception.

Constant i.e. O(1)

In the following example, we are going to consider the basic usage of the empty() function.

#include <iostream>
#include <array>
using namespace std;
int main() {
   array < int, 10 > myarray {9,12,15,18,21,24,27,30,33,36};
   if (myarray.empty()) {
      cout << "True";
   } else {
      cout << "False";
   }
   return 0;
}

Output of the above code is as follows −

False

Consider the following example, where we are going to consider two array one with size zero and another with size 10.

#include <iostream>
#include <array>
using namespace std;
int main(void) {
   array < int, 0 > arr1;
   array < int, 10 > arr2;
   if (arr1.empty())
      cout << "arr1 is empty" << endl;
   else
      cout << "arr1 is not empty" << endl;
   if (arr2.empty())
      cout << "arr2 is empty" << endl;
   else
      cout << "arr2 is not empty" << endl;
}

Following is the output of the above code −

arr1 is empty
arr2 is not empty

array.htm

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