array::empty() in C++ STL with Example

C++ STL array::empty() function with Example: Here, we are going to learn about a library function empty() of array class, which is used to check whether an array is empty or not.
Submitted by IncludeHelp, on November 14, 2018

"array" is a container which is used to create/container which is used to create/contains the fixed size arrays, the "array" in C++ STL is "class" actually and they are more efficient, lightweight and very easy to use, understand, "array" class contains many inbuilt functions, thus the implementation of the operations are fast by using this rather that C-Style arrays.

To use "array" class and its function, we need to include "array" class and its function, we need to include "array" header.

array::empty() function

empty() function is used to check whether an array is empty or not. It returns 1 (true), if the array size is 0 and returns 0 (false), if array size is not zero.

Syntax:

    array_name.empty();

Parameters:

There is no parameter to be passed.

Return type:

1 (true) – if array is empty
0 (false) – if array is not empty

Example:

    Input:
    arr1{} //an empty array
    arr2{10,20,30} //array with 3 elements

    Function calls:
    arr1.empty()
    arr2.empty()

    Output:
    1
    0

Program:

#include <iostream>
#include <array>
using namespace std;

int main() {
	//declaring two arrays 
	array<int,0> arr1{};         
	array<int,5> arr2{};        
	array<int,5> arr3{10, 20, 30};     
	array<int,5> arr4{10, 20, 30, 40, 50};


	//printing arr_name.empty() value
	cout<<"arr1.empty(): "<<arr1.empty()<<endl;
	cout<<"arr2.empty(): "<<arr2.empty()<<endl;
	cout<<"arr3.empty(): "<<arr3.empty()<<endl;
	cout<<"arr4.empty(): "<<arr4.empty()<<endl;

	//checking and printing messages 
	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;
	
	if(arr3.empty())
		cout<<"arr3 is empty"<<endl;
	else
		cout<<"arr3 is not empty"<<endl;
	
	if(arr4.empty())
		cout<<"arr4 is empty"<<endl;
	else
		cout<<"arr4 is not empty"<<endl;

	return 0;
}

Output

arr1.empty(): 1
arr2.empty(): 0
arr3.empty(): 0
arr4.empty(): 0
arr1 is empty
arr2 is not empty
arr3 is not empty
arr4 is not empty