array::operator[ ] in C++ STL

array::at() in C++ STL

Last Updated : 19 Jan, 2018

Array classes are generally more efficient, light-weight and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::at() This function is used to return the reference to the element present at the position given as the parameter to the function. Syntax:

array_name.at(position)

Parameters:
Position of the element to be fetched.

Return: It return the reference to the element at the given position. Examples:

Input:  array_name1 = [1, 2, 3]
        array_name1.at(2);
Output: 3

Input:  array_name2 = ['a', 'b', 'c', 'd', 'e']
        array_name2.at(4);
Output: e

CPP

// CPP program to illustrate
// Implementation of at() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // Take any two array
    array<int, 3> array_name1;
    array<char, 5> array_name2;
    
    // Inserting values
    for (int i = 0; i < 3; i++)
        array_name1[i] = i+1;
    
    for (int i = 0; i < 5; i++)
        array_name2[i] = 97+i;
        
    // Printing the element 
    cout << "Element present at position 2: " 
         << array_name1.at(2) << endl;
    cout << "Element present at position 4: " 
         << array_name2.at(4);
    
    return 0;
}

Output:

Element present at position 2: 3
Element present at position 4: e

Time Complexity: Constant i.e. O(1). Application: Given an array of integers, print integers in alternate fashion starting from 1st position.

Input:  1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Output: 2 4 6 8 10

CPP

// CPP program to illustrate
// application of at() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // Declare array
    array<int, 10> a;
    
    // Inserting values
    for (int i = 0; i < 10; i++)
        a[i] = i+1;
        
    for (int i = 0; i < a.size(); ++i) {
        if (i % 2 != 0) {
            cout << a.at(i);
            cout << " ";
        }
    }
    return 0;
}

Output:

2 4 6 8 10

array::operator[ ] in C++ STL

A

AKASH GUPTA 6

Improve

Article Tags :

Practice Tags :

Similar Reads

STD::array in C++

The array is a collection of homogeneous objects and this array container is defined for constant size arrays or (static size). This container wraps around fixed-size arrays and the information of its size are not lost when declared to a pointer. In order to utilize arrays, we need to include the ar

array::begin() and array::end() in C++ STL

Array classes are generally more efficient, light-weight and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::begin() begin() function is used to return an iterator pointing to the first element of the array containe

array::size() in C++ STL

The array::size() method is used to find the number of elements in the array container. It is the member method std::array class defined inside <array> header file. In this article, we will learn about the array::size() method in C++.Example:C++// C++ Program to illustrate the use of array::si

array::empty() in C++ STL

Array classes are generally more efficient, light-weight and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::empty() empty() function is used to check if the array container is empty or not. Syntax : arrayname.empty

array::front() and array::back() in C++ STL

Array classes are generally more efficient, light-weight, and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::front() This function is used to reference the first element of the array container. This function can be

array::at() in C++ STL

Array classes are generally more efficient, light-weight and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::at() This function is used to return the reference to the element present at the position given as the par

array::operator[ ] in C++ STL

Array classes are generally more efficient, light-weight, and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::operator[] This operator is used to reference the element present at position given inside the operator.

array get() function in C++ STL

The array::get() is a built-in function in C++ STL which returns a reference to the i-th element of the array container. Syntax: get(array_name) Parameters: The function accepts two mandatory parameters which are described below. i - position of an element in the array, with 0 as the position of the

array data() in C++ STL with Examples

The array::data() is a built-in function in C++ STL which returns an pointer pointing to the first element in the array object. Syntax: array_name.data() Parameters: The function does not accept any parameters. Return Value: The function returns an pointer. Below programs illustrate the above functi

array::max_size() in C++ STL

Array classes are generally more efficient, light-weight and reliable than C-style arrays. The introduction of array class from C++11 has offered a better alternative for C-style arrays. array::max_size() This function returns the maximum number of elements that the array container can contain. In c