# std::ranges::contiguous_range

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< cpp‎ | ranges

Defined in header `<ranges>` |  |
template< class T > concept contiguous_range = ranges::random_access_range <T> && std::contiguous_iterator < ranges::iterator_t <T>> && requires(T& t) { { ranges::data (t) } -> std::same_as < std::add_pointer_t < ranges::range_reference_t <T>>>; }; |  | (since C++20)

The `contiguous_range` concept is a refinement of `range` for which ranges::begin returns a model of `contiguous_iterator` and the customization point ranges::data is usable.

### Semantic requirements

`T` models `contiguous_range` only if given an expression `e` such that decltype((e)) is T&, std::to_address ( ranges::begin (e)) == ranges::data (e).

### Example

Run this code

    #include <array>
    #include <deque>
    #include <list>
    #include <mdspan>
    #include <ranges>
    #include <set>
    #include <span>
    #include <string_view>
    #include <valarray>
    #include <vector>

    template<typename T>
    concept CR = std::ranges::contiguous_range<T>;

    // zstring being a ranges::contiguous_range doesn't have to be a ranges::sized_range
    struct zstring
    {
        struct sentinel
        {
            friend constexpr bool operator==(const char* str, sentinel) noexcept
            { return *str == '\0'; }
        };

        const char* str;

        const char* begin() const noexcept { return str; }
        sentinel end() const noexcept { return {}; }
    };

    int main()
    {
        int a[4];
        static_assert(
                CR<std::vector<int>> and
            not CR<std::vector<bool>> and
            not CR<std::deque<int>> and
                CR<std::valarray<int>> and
                CR<decltype(a)> and
            not CR<std::list<int>> and
            not CR<std::set<int>> and
                CR<std::array<std::list<int>,42>> and
                CR<std::string_view> and
                CR<zstring> and
                CR<std::span<const int>> and
            not CR<std::mdspan<int, std::dims<1>>>
        );
    }

### See also

ranges::sized_range (C++20) | specifies that a range knows its size in constant time (concept)
ranges::random_access_range (C++20) | specifies a range whose iterator type satisfies `random_access_iterator` (concept)

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