NAME¶

std::experimental::ranges::difference_type - std::experimental::ranges::difference_type

Synopsis¶

Defined in header <experimental/ranges/iterator>
template< class I > (1)
struct difference_type { };
template< class T > (2)
struct difference_type<T*>;
template< class T > (3)
struct difference_type<const T> : difference_type<std::decay_t<T>> { };
template <class T>

requires requires { typename T::difference_type; } (4)

struct difference_type<T>;
template <class T>

requires !requires { typename T::difference_type; } && (5)
requires(const T& a, const T& b) { { a - b } -> Integral; }

struct difference_type<T>;

Computes the associated difference type of the type I, if any. Users may specialize
difference_type for a program-defined type.

1) Primary template is an empty struct.
2) Specialization for pointers. If T is an object type, provides a member type type
equal to std::ptrdiff_t. Otherwise, there is no member type.
3) Specialization for const-qualified types.
4) Specialization for types that define a public and accessible member type
difference_type. Provides a member type type equal to T::difference_type.
5) Specialization for types that do not define a public and accessible member type
difference_type but do support subtraction. Provides a member type type equal to
std::make_signed_t<decltype(std::declval<T>() - std::declval<T>())>.

Helper alias template

template< class T > (ranges TS)
using difference_type_t = typename ranges::difference_type<T>::type;

Example¶

This section is incomplete
Reason: no example

See also¶

specifies that a Semiregular type can be incremented with pre-
WeaklyIncrementable and post-increment operators
(concept)
compatibility traits class that collects an iterator’s
iterator_traits associated types
(alias template)