Home » C++ STL

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

C++ STL array::size() function with example: Here, we are going to learn about a library function "size()" of "array" class, which is used to return the total number of elements/size of an array.
Submitted by IncludeHelp, on November 10, 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.

C++ STL array::size() function

"size()" function returns the size of the array (Note: "size()" can also be used for other containers like list etc).

Syntax

array_name.size();

Parameter(s)

There is no parameter to be passed.

Return value

Returns size of the array

Sample Input and Output

Input:
arr1{} //an empty array
arr2{10,20,30} //array with 3 elements
    
Function calls:
arr1.size()
arr2.size()
    
Output:
Size of arr1: 0
Size of arr2: 3

Example

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

int main() {
  // declaring two arrays
  array<int, 0> arr1{};                    // an empty array
  array<int, 5> arr2{};                    // array size: 5, elements 0
  array<int, 5> arr3{10, 20, 30};          // array size: 5, elements: 3
  array<int, 5> arr4{10, 20, 30, 40, 50};  // array size:5, elements: 5

  cout << "size of arr1: " << arr1.size() << endl;
  cout << "size of arr2: " << arr2.size() << endl;
  cout << "size of arr3: " << arr3.size() << endl;
  cout << "size of arr4: " << arr4.size() << endl;

  return 0;
}

Output

size of arr1: 0
size of arr2: 5
size of arr3: 5
size of arr4: 5