29 Numerics library [numerics]

29.8 Generalized numeric operations [numeric.ops]

29.8.11 Adjacent difference [adjacent.difference]

template <class InputIterator, class OutputIterator> OutputIterator adjacent_difference(InputIterator first, InputIterator last, OutputIterator result); template <class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2> ForwardIterator2 adjacent_difference(ExecutionPolicy&& exec, ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 result); template <class InputIterator, class OutputIterator, class BinaryOperation> OutputIterator adjacent_difference(InputIterator first, InputIterator last, OutputIterator result, BinaryOperation binary_op); template <class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2, class BinaryOperation> ForwardIterator2 adjacent_difference(ExecutionPolicy&& exec, ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 result, BinaryOperation binary_op);

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Requires:

  • (1.1)

    For the overloads with no ExecutionPolicy, InputIterator's value type shall be MoveAssignable (Table 25) and shall be constructible from the type of *first. acc (defined below) shall be writable ([iterator.requirements.general]) to the result output iterator. The result of the expression val - acc or binary_­op(val, acc) shall be writable to the result output iterator.

  • (1.2)

    For the overloads with an ExecutionPolicy, the value type of ForwardIterator1 shall be CopyConstructible (Table 24), constructible from the expression *first - *first or binary_­op(*first, *first), and assignable to the value type of ForwardIterator2.

  • (1.3)

    For all overloads, in the ranges [first, last] and [result, result + (last - first)], binary_­op shall neither modify elements nor invalidate iterators or subranges.285

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Effects: For the overloads with no ExecutionPolicy and a non-empty range, the function creates an accumulator acc whose type is InputIterator's value type, initializes it with *first, and assigns the result to *result. For every iterator i in [first + 1, last) in order, creates an object val whose type is InputIterator's value type, initializes it with *i, computes val - acc or binary_­op(val, acc), assigns the result to *(result + (i - first)), and move assigns from val to acc.

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For the overloads with an ExecutionPolicy and a non-empty range, first the function creates an object whose type is ForwardIterator1's value type, initializes it with *first, and assigns the result to *result. Then for every d in [1, last - first - 1], creates an object val whose type is ForwardIterator1's value type, initializes it with *(first + d) - *(first + d - 1) or binary_­op(*(first + d), *(first + d - 1)), and assigns the result to *(result + d).

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Returns: result + (last - first).

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Complexity: Exactly (last - first) - 1 applications of the binary operation.

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Remarks: For the overloads with no ExecutionPolicy, result may be equal to first. For the overloads with an ExecutionPolicy, the ranges [first, last) and [result, result + (last - first)) shall not overlap.

285)

The use of fully closed ranges is intentional.