std::array<T,N>::operator[]

	(1)
reference operator[]( size_type pos );			(until C++17)
constexpr reference operator[]( size_type pos );			(since C++17)
		(2)
const_reference operator[]( size_type pos ) const;				(until C++14)
constexpr const_reference operator[]( size_type pos ) const;				(since C++14)

Returns a reference to the element at specified location pos. No bounds checking is performed.

Parameters

pos

-

position of the element to return

Return value

Reference to the requested element.

Complexity

Constant.

Notes

Unlike std::map::operator[], this operator never inserts a new element into the container. Accessing a nonexistent element through this operator is undefined behavior.

Example

The following code uses operator[] to read from and write to a std::array<int>:

Run this code

#include <array>
#include <iostream>
 
int main()
{
    std::array<int,4> numbers {2, 4, 6, 8};
 
    std::cout << "Second element: " << numbers[1] << '\n';
 
    numbers[0] = 5;
 
    std::cout << "All numbers:";
    for (auto i : numbers)
        std::cout << ' ' << i;
    std::cout << '\n';
}

Output:

Second element: 4
All numbers: 5 4 6 8

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