std::set_difference
From Cppreference
| Defined in header <algorithm>
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| template< class InputIterator1, class InputIterator2, class OutputIterator >
OutputIterator set_difference( InputIterator1 first1, InputIterator1 last1, |
(1) | |
| template< class InputIterator1, class InputIterator2,
class OutputIterator, class Compare > |
(2) | |
Copies the elements from the sorted range [first1, last1) which are not found in the sorted range [first2, last2) to the range beginning at d_first. The resulting range is also sorted. The first version expects both input ranges to be sorted with operator<, the second version expects them to be sorted with the given comparison function comp. Equivalent elements are treated individually, that is, if some element is found m times in [first1, last1) and n times in [first2, last2), it will be copied to d_first exactly std::min(m-n, 0) times. The resulting range cannot overlap with either of the input ranges.
Contents |
[edit] Parameters
| first1, last1 | - | the range of elements to examine | |||||||||
| first2, last2 | - | the range of elements to search for | |||||||||
| comp | - | comparison function which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have const &, but the function must not modify the objects passed to it. |
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[edit] Return value
Iterator past the end of the constructed range.
[edit] Complexity
At most 2·(N1+N2-1) comparisons, where N1 = std::distance(first1, last1) and N2 = std::distance(first2, last2).
[edit] Equivalent function
| First version |
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template<class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_difference(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator d_first) { while (first1 != last1) { if (first2 == last2) return std::copy(first1, last1, d_first); if (*first1 < *first2) { *d_first++ = *first1++; } else { if (! (*first2 < *first1)) { ++first1; } ++first2; } } return d_first; } |
| Second version |
template<class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_difference( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator d_first, Compare comp) { while (first1 != last1) { if (first2 == last2) return std::copy(first1, last1, d_first); if (comp(*first1, *first2)) { *d_first++ = *first1++; } else { if (!comp(*first2, *first1)) { ++first1; } ++first2; } } return d_first; } |
[edit] Example
| This section is incomplete |
[edit] See also
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returns true if one set is a subset of another (function template) |
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computes the symmetric difference between two sets (function template) |
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