23 Algorithms library [algorithms]

23.5 Non-modifying sequence operations [alg.nonmodifying]

23.5.11 Equal [alg.equal]

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template<class InputIterator1, class InputIterator2> constexpr bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2); template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2> bool equal(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2); template<class InputIterator1, class InputIterator2, class BinaryPredicate> constexpr bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, BinaryPredicate pred); template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2, class BinaryPredicate> bool equal(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, BinaryPredicate pred); template<class InputIterator1, class InputIterator2> constexpr bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2); template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2> bool equal(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2); template<class InputIterator1, class InputIterator2, class BinaryPredicate> constexpr bool equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, BinaryPredicate pred); template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2, class BinaryPredicate> bool equal(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
1
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Remarks: If last2 was not given in the argument list, it denotes first2 + (last1 - first1) below.
2
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Returns: If last1 - first1 != last2 - first2, return false.
Otherwise return true if for every iterator i in the range [first1, last1) the following corresponding conditions hold: *i == *(first2 + (i - first1)), pred(*i, *(first2 + (i - first1))) != false.
Otherwise, returns false.
3
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Complexity:
  • (3.1)
    For the overloads with no ExecutionPolicy,
    • (3.1.1)
      if InputIterator1 and InputIterator2 meet the Cpp17RandomAccessIterator requirements ([random.access.iterators]) and last1 - first1 != last2 - first2, then no applications of the corresponding predicate; otherwise,
    • (3.1.2)
      at most applications of the corresponding predicate.
  • (3.2)
    For the overloads with an ExecutionPolicy,
    • (3.2.1)
      if ForwardIterator1 and ForwardIterator2 meet the Cpp17RandomAccessIterator requirements and last1 - first1 != last2 - first2, then no applications of the corresponding predicate; otherwise,
    • (3.2.2)
      applications of the corresponding predicate.