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std::unique

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Algorithm Bibliothek
Funktionen
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Functions
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Nicht-modifizierende Sequenz Operationen
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Non-modifying sequence operations
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Modifizierende Sequenz Operationen
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Modifying sequence operations
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Partitionierungsoperationen
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Partitioning operations
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Sortierung Operationen (auf sortierten Bereiche)
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Sorting operations (on sorted ranges)
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Binary Suchaktionen (auf sortierten Bereiche)
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Binary search operations (on sorted ranges)
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Set-Operationen (auf sortierten Bereiche)
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Set operations (on sorted ranges)
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Heap-Operationen
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Heap operations
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Minimum / Maximum Operationen
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Minimum/maximum operations
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Numerische Operationen
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Numeric operations
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C-Bibliothek
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C library
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Defined in header <algorithm>
template< class ForwardIt >
ForwardIt unique( ForwardIt first, ForwardIt last );
(1)
template< class ForwardIt, class BinaryPredicate >
ForwardIt unique( ForwardIt first, ForwardIt last, BinaryPredicate p );
(2)
Entfernt alle aufeinander doppelte Elemente aus dem Bereich [first, last). Entfernen wird durch Verschieben des Bereichs, wenn in der Weise, dass Elemente, die gelöscht werden überschrieben werden benötigt getan. Nur das erste Element in jeder Gruppe von Elementen gleich bleibt. Die Elemente zwischen dem alten und dem neuen Ende oder Bereich sind intakt gelassen. Die erste Version verwendet operator== um die Elemente zu vergleichen, verwendet die zweite Version des gegebenen binären Prädikats p .
Original:
Removes all consecutive duplicate elements from the range [first, last). Removing is done by shifting the range when needed in such a way that elements to be erased are overwritten. Only the first element in each group of equal elements is left. The elements between the old and the new end or the range are left intact. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.
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Inhaltsverzeichnis

[Bearbeiten] Parameter

first, last -
der Bereich der Elemente zu verarbeiten
Original:
the range of elements to process
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p - binary predicate which returns ​true if the elements should be treated as equal.

The signature of the predicate function should be equivalent to the following:

 bool pred(const Type1 &a, const Type2 &b);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The types  Type1 and  Type2 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to both of them.

Type requirements
-
ForwardIt must meet the requirements of ForwardIterator.
-
The type of dereferenced ForwardIt must meet the requirements of MoveAssignable.

[Bearbeiten] Rückgabewert

Forward-Iterator auf das neue Ende des Bereichs
Original:
Forward iterator to the new end of the range
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[Bearbeiten] Mögliche Implementierung

First version
template<class ForwardIt>
ForwardIt unique(ForwardIt first, ForwardIt last)
{
    if (first == last)
        return last;
 
    ForwardIt result = first;
    while (++first != last) {
        if (!(*result == *first)) {
            *(++result) = *first;
        }
    }
    return ++result;
}
Second version
template<class ForwardIt, class BinaryPredicate>
ForwardIt unique(ForwardIt first, ForwardIt last, 
                       BinaryPredicate p)
{
    if (first == last)
        return last;
 
    ForwardIt result = first;
    while (++first != last) {
        if (!p(*result, *first)) {
            *(++result) = *first;
        }
    }
    return ++result;
}

[Bearbeiten] Beispiel

Der folgende Code entfernt alle aufeinanderfolgenden gleichwertige Elemente aus einem Vektor von ganzen Zahlen .
Original:
The following code removes all consecutive equivalent elements from a vector of integers.
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#include <iostream>
#include <algorithm>
#include <vector>
 
int main() 
{
    std::vector<int> v{1, 2, 2, 2, 3, 3, 2, 2, 1};
    std::vector<int>::iterator last;
 
    last = std::unique(v.begin(), v.end()); // 1 2 3 2 1 3 2 2 1
                                            //           ^
    for (std::vector<int>::iterator it = v.begin(); it != last; ++it) {
        std::cout << *it << " ";
    }
    std::cout << "\n";
}

Output:

1 2 3 2 1

[Bearbeiten] Komplexität

linear im Abstand first und last
Original:
linear in the distance between first and last
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[Bearbeiten] Siehe auch

findet zwei identischen (oder eine andere Beziehung) Elemente einander benachbart
Original:
finds two identical (or some other relationship) items adjacent to each other
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(Funktions-Template) [edit]
erstellt eine Kopie von einigen Reihe von Elementen, die keine Folge Duplikate enthält
Original:
creates a copy of some range of elements that contains no consecutive duplicates
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(Funktions-Template) [edit]