# std::vector<T,Allocator>::operator[]

From cppreference.com
< cpp‎ | container‎ | vector

reference operator[]( size_type pos ); |  |
const_reference operator[]( size_type pos ) const; |  |

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.

### Example

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

Run this code

    #include <vector>
    #include <iostream>

    int main()
    {
        std::vector<int> 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

### See also

at | access specified element with bounds checking (public member function)

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