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array::operator[] with Example in C++ STL

C++ STL | array::operator[]: Here, we are going to learn about the operator [] of Array in C++ STL.
Submitted by IncludeHelp, on February 28, 2019

C++ STL array::operator[]

Operator [] is used to get/set the element of an array in C++ STL, it returns a reference to an element at given index.

Syntax

array_name[index];

Parameter(s)

index - position of an element.

Return value

It returns a reference to the element at given index.

Sample Input and Output

Input or array declaration:
array<int,5> values {10, 20, 30, 40, 50};

Output:
values[0]	:	10
values[1]	:	20

Example

C++ STL program to demonstrate example of array:operator[] −

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

int main() {
  array<int, 5> values{10, 20, 30, 40, 50};

  // printing elements
  cout << "element at index 0: " << values[0] << endl;
  cout << "element at index 1: " << values[1] << endl;
  cout << "element at index 2: " << values[2] << endl;
  cout << "element at index 3: " << values[3] << endl;
  cout << "element at index 4: " << values[4] << endl;

  // changing some of the values
  values[0] = 100;
  values[4] = 500;

  // printing all elements
  cout << "All elements:" << endl;
  for (int i : values) {
    cout << i << " ";
  }
  cout << endl;

  return 0;
}

Output

element at index 0: 10
element at index 1: 20
element at index 2: 30
element at index 3: 40
element at index 4: 50
All elements:
100 20 30 40 500