std::partition_copy - cppreference.com

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Elemento definito nell'header `<algorithm>`

`template< class InputIt, class OutputIt1, class OutputIt2, class UnaryPredicate > std::pair<OutputIt1, OutputIt2> partition_copy(InputIt first, InputIt last, OutputIt1 d_first_true, OutputIt2 d_first_false, UnaryPredicate p);`		(dal C++11)

Copia gli elementi che soddisfano la p predicato dal [first, last) gamma all'inizio gamma a d_first_true, e copia gli elementi che non soddisfano p all'inizio gamma a d_first_false.

Original:

Copies the elements that satisfy the predicate p from the range [first, last) to the range beginning at d_first_true, and copies the elements that do not satisfy p to the range beginning at d_first_false.

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Parametri

first, last	-	la gamma di elementi da ordinare Original: the range of elements to sort The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
d_first_true	-	l'inizio del campo di uscita per gli elementi che soddisfano p Original: the beginning of the output range for the elements that satisfy p The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
d_first_false	-	l'inizio del campo di uscita per gli elementi che non soddisfano p Original: the beginning of the output range for the elements that do not satisfy p 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` se l'elemento deve essere posto in d_first_true Original: if the element should be placed in d_first_true 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 `InputIt` can be dereferenced and then implicitly converted to `Type`.
Type requirements
-`InputIt` must meet the requirements of `InputIterator`.
-`OutputIt1` must meet the requirements of `OutputIterator`.
-`OutputIt2` must meet the requirements of `OutputIterator`.

Valore di ritorno

Un pair costruito dal iteratore alla fine del campo d_first_true e l'iteratore alla fine del campo d_first_false.

Original:

A pair constructed from the iterator to the end of the d_first_true range and the iterator to the end of the d_first_false range.

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Complessità

Esattamente distance(first, last) applicazioni di p.

Original:

Exactly distance(first, last) applications of p.

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Possibile implementazione

template<class InputIt, class OutputIt1,
         class OutputIt2, class UnaryPredicate>
std::pair<OutputIt1, OutputIt2>
    partition_copy(InputIt first, InputIt last,
                   OutputIt1 d_first_true, OutputIt2 d_first_false,
                   UnaryPredicate p)
{
    while (first != last) {
        if (p(*first)) {
            *d_first_true = *first;
            ++d_first_true;
        } else {
            *d_first_false = *first;
            ++d_first_false;
        }
        ++first;
    }
    return std::pair<OutputIt1, OutputIt2>(d_first_true, d_first_false);
}

Esempio

#include <iostream>
#include <algorithm>
#include <utility>

int main()
{
    int arr [10] = {1,2,3,4,5,6,7,8,9,10};
    int true_arr [5] = {0};
    int false_arr [5] = {0};

    std::partition_copy(std::begin(arr), std::end(arr), std::begin(true_arr),std::begin(false_arr),
                        [] (int i) {return i > 5;});

    std::cout << "true_arr: ";
    for (auto it = std::begin(true_arr); it != std::end(true_arr); ++it) {
        std::cout << *it << ' ';
    }
    std::cout << '\n'; 

    std::cout << "false_arr: ";
    for (auto it = std::begin(false_arr); it != std::end(false_arr); ++it) {
        std::cout << *it << ' ';
    }
    std::cout << '\n'; 

    return 0;

}

Output:

true_arr: 6 7 8 9 10
false_arr: 1 2 3 4 5

Vedi anche


	divide una serie di elementi in due gruppi Original: divides a range of elements into two groups The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello) [modifica]

	divide gli elementi in due gruppi, mantenendo l'ordine relativo 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. (funzione di modello) [modifica]