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std::for_each

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< cpp‎ | algorithm

 
 
Biblioteca algoritmo
Funções
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Functions
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Não modificar operações de seqüência
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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
Modificando operações de seqüência
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Modifying sequence operations
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Particionamento operações
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Partitioning operations
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Operações de classificação (em intervalos ordenados)
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Sorting operations (on sorted ranges)
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Binários operações de busca (em intervalos ordenados)
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Binary search operations (on sorted ranges)
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Definir operações (em intervalos ordenados)
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Set operations (on sorted ranges)
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Operações de pilha
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Heap operations
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Mínimo / máximo de operações
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Minimum/maximum operations
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Operações numéricas
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Numeric operations
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C biblioteca
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C library
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Defined in header <algorithm>
template< class InputIt, class UnaryFunction >
UnaryFunction for_each( InputIt first, InputIt last, UnaryFunction f );
Aplica-se a f determinado objeto função do resultado de cada dereferencing iterador na [first, last) gama, em ordem. Se InputIt é mutável iterador, f pode modificar os elementos da gama através do iterador dereferenced. Se f retorna um resultado, o resultado é ignorado.
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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Índice

[editar] Parâmetros

first, last -
a gama de aplicar a função de
Original:
the range to apply the function to
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f -
o objeto de função unária a ser aplicada
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

[editar] Valor de retorno

f. (até C + 11)
std::move(f). (a partir do C++ 11)

[editar] Complexidade

Exactamente last - first aplicações de f
Original:
Exactly last - first applications of f
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[editar] Possível implementação

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

[editar] Exemplo

O exemplo a seguir utiliza um função lambda para aumentar todos os elementos de um vector e, em seguida, calcula uma soma deles:
Original:
The following example uses a função lambda 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

[editar] Veja também

aplica-se uma função de uma série de elementos
Original:
applies a function to a range of elements
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(modelo de função) [edit]
faixa para loop
executa loop sobre (a partir do C++ 11) alcance
Original:
executes loop over range (a partir do C++ 11)
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[edit]