std::replace_copy, std::replace_copy_if - cppreference.com

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Elemento definito nell'header `<algorithm>`

`template< class InputIt, class OutputIt, class T > OutputIt replace_copy( InputIt first, InputIt last, OutputIt d_first, const T& old_value, const T& new_value );`	(1)

`template< class InputIt, class OutputIt, class UnaryPredicate, class T > OutputIt replace_copy_if( InputIt first, InputIt last, OutputIt d_first, UnaryPredicate p, const T& new_value );`	(2)

Copies the all elements from the range [first, last) to another range beginning at d_first replacing all elements satisfying specific criteria with new_value. The first version replaces the elements that are equal to old_value, the second version replaces elements for which predicate p returns true. The source and destination ranges cannot overlap.

Parametri

first, last	-	dell'intervallo di elementi da copiare Original: the range of elements to copy The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
d_first	-	l'inizio del campo di destinazione Original: the beginning of the destination range The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
old_value	-	il valore di elementi da sostituire Original: the value of elements to replace 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 il valore dell'elemento deve essere sostituito Original: if the element value should be replaced 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`.
new_value	-	il valore da utilizzare come ricambio Original: the value to use as replacement The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Type requirements
-`InputIt` must meet the requirements of `InputIterator`.
-`OutputIt` must meet the requirements of `OutputIterator`.

Valore di ritorno

Iterator all'elemento passato l'ultimo elemento copiato.

Original:

Iterator to the element past the last element copied.

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Complessità

Esattamente last - first applicazioni del predicato.

Original:

Exactly last - first applications of the predicate.

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Possibile implementazione

First version
template<class InputIt, class OutputIt, class T> OutputIt replace_copy(InputIt first, InputIt last, OutputIt d_first, const T& old_value, const T& new_value) { for (; first != last; ++first) { d_first++ = (first == old_value) ? new_value : *first; } return d_first; }
Second version
template<class InputIt, class OutputIt, class UnaryPredicate, class T> OutputIt replace_copy_if(InputIt first, InputIt last, OutputIt d_first, UnaryPredicate p, const T& new_value) { for (; first != last; ++first) { d_first++ = (p( first ) ? new_value : *first; } return d_first; }

First version

template<class InputIt, class OutputIt, class T>
OutputIt replace_copy(InputIt first, InputIt last, OutputIt d_first,
                      const T& old_value, const T& new_value)
{
    for (; first != last; ++first) {
        *d_first++ = (*first == old_value) ? new_value : *first;
    }
    return d_first;
}

Second version

template<class InputIt, class OutputIt, 
         class UnaryPredicate, class T>
OutputIt replace_copy_if(InputIt first, InputIt last, OutputIt d_first,
                         UnaryPredicate p, const T& new_value)
{
    for (; first != last; ++first) {
        *d_first++ = (p( *first ) ? new_value : *first;
    }
    return d_first;
}

Esempio

The following copy prints a vector, replacing all values over 5 with 99 on the fly.

#include <algorithm>
#include <vector>
#include <iostream>
#include <iterator>
#include <functional>

int main()
{
    std::vector<int> v{5, 7, 4, 2, 8, 6, 1, 9, 0, 3};
    std::replace_copy_if(v.begin(), v.end(),
                         std::ostream_iterator<int>(std::cout, " "),
                         [](int n){return n > 5;}, 99);
    std::cout << '\n';
}

Output:

Vedi anche


	rimuove gli elementi che soddisfano criteri specifici Original: removes elements satisfying specific criteria 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]