# std::ranges::view_interface<D>::operator[]

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< cpp‎ | ranges‎ | view interface

template<ranges::random_access_range R = D> constexpr decltype(auto) operator[]( ranges::range_difference_t<R> n ); | (1) | (since C++20)
template<ranges::random_access_range R = const D> constexpr decltype(auto) operator[]( ranges::range_difference_t<R> n ) const; | (2) | (since C++20)

The default implementation of operator[] member function obtains the element at the specified offset relative to the beginning iterator, reusing the operator[] of the iterator type.

1) Let `derived` be static_cast<D&>(*this). Equivalent to return ranges::begin(derived)[n];.
2) Same as (1), except that `derived` is static_cast<const D&>(*this).

### Parameters

n | - | position of the element to return

### Return value

The element at offset `n` relative to the beginning iterator.

### Notes

In C++20, no type derived from std::ranges::view_interface in the standard library provides their own operator[] member function.

However, following derived types cannot use the default implementations, as they never satisfy `random_access_range`:

- std::ranges::basic_istream_view
- std::ranges::filter_view
- std::ranges::join_view
- std::ranges::lazy_split_view
- std::ranges::split_view

The inherited operator[] member function is available for std::ranges::empty_view, but a call to it always results in undefined behavior.

### Example

| This section is incomplete Reason: no example

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