# std::ranges::view::counted

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< cpp‎ | ranges

namespace view { inline constexpr /*unspecified*/ counted = /*unspecified*/; } |  | (since C++20)

A counted view presents a `View` of the elements of the counted range `[i, n)` for some iterator `i` and non-negative integer `n`.

A counted range `[i, n)` is the `n` elements starting with the element pointed to by `i` and up to but not including the element, if any, pointed to by the result of `n` applications of ++i.

If `n == 0`, the counted range is valid and empty. Otherwise, the counted range is only valid if n is positive, i is dereferenceable, and [++i, --n) is a valid counted range.

Formally, if `E` and `F` are expressions, and `T` is the type std::decay_t<decltype((E))>, then

  if `T` models `Iterator` and decltype((F)) models ConvertibleTo<iter_difference_t<T>>,
    if T models `RandomAccessIterator`, view::counted(E, F) is expression-equivalent to ranges::subrange{E, E + static_cast<std::iter_difference_t<T>>(F)}
    otherwise view::counted(E, F) is expression-equivalent to ranges::subrange{std::counted_iterator{E, F}, std::default_sentinel}
  otherwise, view::counted(E, F) is ill-formed.

### Example

Run this code

    #include <ranges>
    #include <iostream>

    int main()
    {
      int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
      for(int i : std::view::counted(a, 3))
        std::cout << i << ' ';
    }

Output:

    1 2 3

### See also

subrange | combines an iterator-sentinel pair into a `View` (class template)
counted_iterator (C++20) | iterator adaptor that tracks the distance to the end of the range (class template)

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