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std::replace, std::replace_if

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C++
 
Algoritmo libreria
Funzioni
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Functions
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Non modifica le operazioni di sequenza
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Non-modifying sequence operations
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Modifica delle operazioni di sequenza
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Modifying sequence operations
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Partizionamento operazioni
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Partitioning operations
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Ordinamento delle operazioni (su intervalli ordinati)
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Sorting operations (on sorted ranges)
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Binarie (le operazioni di ricerca sui campi ordinati)
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Binary search operations (on sorted ranges)
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Impostare le operazioni (su intervalli ordinati)
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Set operations (on sorted ranges)
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Heap operazioni
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Heap operations
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Minimo / massimo le operazioni
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Minimum/maximum operations
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Operazioni numeriche
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Numeric operations
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Libreria C
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C library
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Elemento definito nell'header <algorithm>
template< class ForwardIt, class T >

void replace( ForwardIt first, ForwardIt last,

              const T& old_value, const T& new_value );
 (1)
template< class ForwardIt, class UnaryPredicate, class T >

void replace_if( ForwardIt first, ForwardIt last,

                 UnaryPredicate p, const T& new_value );
 (2)
Sostituisce tutti gli elementi che soddisfano criteri specifici con new_value nel [first, last) gamma. La prima versione sostituisce gli elementi che sono uguali a old_value, la seconda versione sostituisce gli elementi per i quali predicato p ritorna true.
Original:
Replaces all elements satisfying specific criteria with new_value in the range [first, last). The first version replaces the elements that are equal to old_value, the second version replaces elements for which predicate p returns true.
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Indice

[modifica] Parametri

first, last -
l'intervallo di elementi di processo
Original:
the range of elements to process
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old_value -
il valore di elementi da sostituire
Original:
the value of elements to replace
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p - unary predicate which returns ​true
se il valore dell'elemento deve essere sostituito
Original:
if the element value should be replaced
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.

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. ​

new_value -
il valore da utilizzare come ricambio
Original:
the value to use as replacement
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Type requirements
-
ForwardIt must meet the requirements of ForwardIterator.

[modifica] Valore di ritorno

(Nessuno)
Original:
(none)
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[modifica] Complessità

Esattamente last - first applicazioni del predicato.
Original:
Exactly last - first applications of the predicate.
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[modifica] Possibile implementazione

First version 
template<class ForwardIt, class T>
void replace(ForwardIt first, ForwardIt last,
             const T& old_value, const T& new_value)
{
    for (; first != last; ++first) {
        if (*first == old_value) {
            *first = new_value;
        }
    }
}
Second version 
template<class ForwardIt, class UnaryPredicate, class T>
void replace_if(ForwardIt first, ForwardIt last,
                UnaryPredicate p, const T& new_value)
{
    for (; first != last; ++first) {
        if(p(*first)) {
            *first = new_value;
        }
    }
}

[modifica] Esempio

Il codice riportato di seguito in un primo momento sostituisce tutte le occorrenze di 8 con 88 in un vettore di interi. Poi sostituisce tutti i valori inferiori 5 con 55 .
Original:
The following code at first replaces all occurrences of 8 with 88 in a vector of integers. Then it replaces all values less than 5 with 55.
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#include <algorithm>
#include <array>
#include <iostream>
#include <functional>
 
int main()
{
    std::array<int, 10> s{5, 7, 4, 2, 8, 6, 1, 9, 0, 3};
 
    std::replace(s.begin(), s.end(), 8, 88);
 
    for (int a : s) {
        std::cout << a << " ";
    }
    std::cout << '\n';
 
    std::replace_if(s.begin(), s.end(), 
                    std::bind(std::less<int>(), std::placeholders::_1, 5), 55);
    for (int a : s) {
        std::cout << a << " ";
    }
    std::cout << '\n';
}

Output: 

5 7 4 2 88 6 1 9 0 3
5 7 55 55 99 6 55 9 55 55

[modifica] Vedi anche
copia un intervallo, la sostituzione degli elementi che soddisfano i criteri specifici con un altro valore
Original:
copies a range, replacing elements satisfying specific criteria with another value
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(funzione di modello) [modifica]
Estratto da "https://it.cppreference.com/mwiki/index.php?title=cpp/algorithm/replace&oldid=24980"