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std::for_each

Da cppreference.com.
< cpp‎ | algorithm

 
 
Algoritmo libreria
Funzioni
Original:
Functions
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Non modifica le operazioni di sequenza
Original:
Non-modifying sequence operations
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all_of
any_of
none_of
(C++11)
(C++11)
(C++11)
for_each
count
count_if
mismatch
equal
Modifica delle operazioni di sequenza
Original:
Modifying sequence operations
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Partizionamento operazioni
Original:
Partitioning operations
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Ordinamento delle operazioni (su intervalli ordinati)
Original:
Sorting operations (on sorted ranges)
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Binarie (le operazioni di ricerca sui campi ordinati)
Original:
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
Original:
C library
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Defined in header <algorithm>
template< class InputIt, class UnaryFunction >
UnaryFunction for_each( InputIt first, InputIt last, UnaryFunction f );
Applica la data f oggetto funzione al risultato di dereference ogni iteratore nel [first, last) campo, in ordine. Se InputIt è un mutevole iteratore, f può modificare gli elementi della gamma attraverso l'iteratore dereferenziato. Se f restituisce un risultato, il risultato viene ignorato.
Original:
Applies the given function object f to the result of dereferencing every iterator in the range [first, last), in order. If InputIt is a mutable iterator, f may modify the elements of the range through the dereferenced iterator. If f returns a result, the result is ignored.
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Indice

[modifica] Parametri

first, last -
la gamma per applicare la funzione
Original:
the range to apply the function to
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f -
l'oggetto funzione unario da applicare
Original:
the unary function object to be applied
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Type requirements
-
InputIt must meet the requirements of InputIterator.
-
UnaryFunction must meet the requirements of MoveConstructible. Does not have to be CopyConstructible

[modifica] Valore di ritorno

f. (C fino + 11)
std::move(f). (dal C++11)

[modifica] Complessità

Esattamente last - first applicazioni di f
Original:
Exactly last - first applications of f
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[modifica] Possibile implementazione

template<class InputIt, class UnaryFunction>
UnaryFunction for_each(InputIt first, InputIt last, UnaryFunction f)
{
    for (; first != last; ++first) {
        f(*first);
    }
    return f;
}

[modifica] Esempio

L'esempio seguente utilizza un lambda funzione per incrementare tutti gli elementi di un vettore e quindi calcola una somma di essi:
Original:
The following example uses a lambda funzione to increment all of the elements of a vector and then computes a sum of them:
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#include <vector>
#include <algorithm>
#include <iostream>
 
struct Sum {
    Sum() { sum = 0; }
    void operator()(int n) { sum += n; }
 
    int sum;
};
 
int main()
{
    std::vector<int> nums{3, 4, 2, 9, 15, 267};
 
    std::cout << "before: ";
    for (auto n : nums) {
        std::cout << n << " ";
    }
    std::cout << '\n';
 
    std::for_each(nums.begin(), nums.end(), [](int &n){ n++; });
    Sum s = std::for_each(nums.begin(), nums.end(), Sum());
 
    std::cout << "after:  ";
    for (auto n : nums) {
        std::cout << n << " ";
    }
    std::cout << '\n';
    std::cout << "sum: " << s.sum << '\n';
}

Output:

before: 3 4 2 9 15 267
after:  4 5 3 10 16 268
sum: 306

[modifica] Vedi anche

applica una funzione di una serie di elementi
Original:
applies a function to a range of elements
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(funzione di modello) [edit]
gamma-ciclo for
esegue un ciclo su (dal C++11) gamma
Original:
executes loop over range (dal C++11)
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[edit]