std::experimental::ranges::RandomAccessIterator(3) | C++ Standard Libary | std::experimental::ranges::RandomAccessIterator(3) |

# NAME¶

std::experimental::ranges::RandomAccessIterator - std::experimental::ranges::RandomAccessIterator

# Synopsis¶

Defined in header <experimental/ranges/iterator>

template< class I >

concept bool RandomAccessIterator =

BidirectionalIterator<I> &&

DerivedFrom<ranges::iterator_category_t<I>,

ranges::random_access_iterator_tag> &&

StrictTotallyOrdered<I> &&

SizedSentinel<I, I> &&

requires(I i, const I j, const ranges::difference_type_t<I> n) {
(ranges TS)

{ i += n } -> Same<I>&;

{ j + n } -> Same<I>&&;

{ n + j } -> Same<I>&&;

{ i -= n } -> Same<I>&;

{ j - n } -> Same<I>&&;

j[n];

requires Same<decltype(j[n]), ranges::reference_t<I>>;

};

The concept RandomAccessIterator<I> refines BidirectionalIterator by
adding support

for constant time advancement with the +=, +, -=, and - operators, constant
time

computation of distance with -, and array notation with subscripting.

Let a and b be valid iterators of type I such that b is reachable from a, and
let n

be a value of type ranges::difference_type_t<I> equal to b - a.

RandomAccessIterator<I> is satisfied only if:

* (a += n) is equal to b.

* std::addressof(a += n) is equal to std::addressof(a).

* (a + n) is equal to (a += n).

* (a + n) is equal to (n + a).

* For any two positive integers x and y, if a + (x + y) is valid, then a + (x
+ y)

is equal to (a + x) + y.

* a + 0 is equal to a.

* If (a + (n - 1)) is valid, then --b is equal to (a + (n - 1)).

* (b += -n) and (b -= n) are both equal to a.

* std::addressof(b -= n) is equal to std::addressof(b).

* (b - n) is equal to (b -= n).

* If b is dereferenceable, then a[n] is valid and is equal to *b.

* bool(a <= b) is true .

Equality preservation

An expression is equality preserving if it results in equal outputs given
equal

inputs.

* The inputs to an expression consist of its operands.

* The outputs of an expression consist of its result and all operands
modified by

the expression (if any).

Every expression required to be equality preserving is further required to be

stable: two evaluations of such an expression with the same input objects
must have

equal outputs absent any explicit intervening modification of those input
objects.

Unless noted otherwise, every expression used in a requires-expression is
required

to be equality preserving and stable, and the evaluation of the expression
may only

modify its non-constant operands. Operands that are constant must not be
modified.

Implicit expression variations

A requires-expression that uses an expression that is non-modifying for some

constant lvalue operand also implicitly requires additional variations of
that

expression that accept a non-constant lvalue or (possibly constant) rvalue
for the

given operand unless such an expression variation is explicitly required with

differing semantics. These implicit expression variations must meet the same

semantic requirements of the declared expression. The extent to which an

implementation validates the syntax of the variations is unspecified.

2024.06.10 | http://cppreference.com |