Namensräume
Varianten
Aktionen

std::partition

Aus cppreference.com
< cpp‎ | algorithm

 
 
Algorithm Bibliothek
Funktionen
Original:
Functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Nicht-modifizierende Sequenz Operationen
Original:
Non-modifying sequence operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Modifizierende Sequenz Operationen
Original:
Modifying sequence operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Partitionierungsoperationen
Original:
Partitioning operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
is_partitioned(C++11)
partition
partition_copy(C++11)
Sortierung Operationen (auf sortierten Bereiche)
Original:
Sorting operations (on sorted ranges)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Binary Suchaktionen (auf sortierten Bereiche)
Original:
Binary search operations (on sorted ranges)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Set-Operationen (auf sortierten Bereiche)
Original:
Set operations (on sorted ranges)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Heap-Operationen
Original:
Heap operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Minimum / Maximum Operationen
Original:
Minimum/maximum operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Numerische Operationen
Original:
Numeric operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
C-Bibliothek
Original:
C library
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
 
Defined in header <algorithm>
template< class BidirIt, class UnaryPredicate >

BidirectionalIterator partition( BidirIt first, BidirIt last,
                                 UnaryPredicate p );
template< class ForwardIt, class UnaryPredicate >
ForwardIt partition( ForwardIt first, ForwardIt last,

                     UnaryPredicate p );
(bis C + +11)

(seit C++11)
Ordnet die Elemente im Bereich [first, last) derart, daß alle Elemente für die das Prädikat p kehrt true vorausgehen, für die die Elemente Prädikats p kehrt false. Relative Reihenfolge der Elemente ist nicht erhalten .
Original:
Reorders the elements in the range [first, last) in such a way that all elements for which the predicate p returns true precede the elements for which predicate p returns false. Relative order of the elements is not preserved.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Inhaltsverzeichnis

[Bearbeiten] Parameter

first, last -
der Bereich von Elementen neu zu ordnen
Original:
the range of elements to reorder
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
p - unary predicate which returns ​true
wenn das Element sollte vor anderen Elementen bestellt werden
Original:
if the element should be ordered before other elements
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
.

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

 bool pred(const Type &a);

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

Type requirements
-
BidirIt must meet the requirements of BidirectionalIterator.
-
ForwardIt must meet the requirements of ValueSwappable and ForwardIterator. However, the operation is more efficient if ForwardIt also satisfies the requirements of BidirectionalIterator

[Bearbeiten] Rückgabewert

Iterator auf das erste Element der zweiten Gruppe .
Original:
Iterator to the first element of the second group.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[Bearbeiten] Komplexität

Genau last-first Anwendungen des Prädikats und höchstens last-first Swaps. Wenn ForwardIt erfüllt die Anforderungen der BidirectionalIterator höchstens (last-first)/2 Swaps fertig sind .
Original:
Exactly last-first applications of the predicate and at most last-first swaps. If ForwardIt meets the requirements of BidirectionalIterator at most (last-first)/2 swaps are done.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[Bearbeiten] Mögliche Implementierung

template<class BidirIt, class UnaryPredicate>
BidirIt partition(BidirIt first, BidirIt last, UnaryPredicate p)
{
    while (1) {
        while ((first != last) && p(*first)) {
            ++first;
        }
        if (first == last--) break;
        while ((first != last) && !p(*last)) {
            --last;
        }
        if (first == last) break;
        std::swap(*first++, *last);
    }
    return first;
}

[Bearbeiten] Beispiel

#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <vector>
 
bool is_even(int i) { return i % 2 == 0; }
 
int main()
{
    std::vector<int> v;
    for (int i = 0; i < 10; ++i) v.push_back(i);
 
    std::cout << "Original vector:\n    ";
    std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
 
    // Partition the vector
    std::vector<int>::iterator p =
        std::partition(v.begin(), v.end(), std::ptr_fun(is_even));
 
    std::cout << "\nPartitioned vector:\n    ";
    std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\nBefore partition:\n    ";
    std::copy(v.begin(), p,       std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\nAfter partition:\n    ";
    std::copy(p,         v.end(), std::ostream_iterator<int>(std::cout, " "));
}

Possible output:

Original vector:
    0 1 2 3 4 5 6 7 8 9 
Partitioned vector:
    0 8 2 6 4 5 3 7 1 9 
Before partition:
    0 8 2 6 4 
After partition:
    5 3 7 1 9

[Bearbeiten] Siehe auch

bestimmt, ob der Bereich von der gegebenen Prädikat partitioniert ist
Original:
determines if the range is partitioned by the given predicate
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(Funktions-Template) [edit]
trennt Elemente in zwei Gruppen unter Beibehaltung ihrer relativen Ordnung
Original:
divides elements into two groups while preserving their relative order
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(Funktions-Template) [edit]