C++ Array::empty() Function

---

---

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).

Syntax

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

 constexpr bool empty() noexcept; 

Parameters

This does not accepts any parameter.

Return Value

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

Exceptions

This function never throws exception.

Time complexity

Constant i.e. O(1)

Example 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

Output of the above code is as follows −

 False 

Example 2

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; } 

Output

Following is the output of the above code −

 arr1 is empty arr2 is not empty