std::for_each – cppreference.com

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definiert in Header `<algorithm>`

`template< class InputIt, class UnaryFunction > UnaryFunction for_each( InputIt first, InputIt last, UnaryFunction f );`

Wendet die angegebene Funktion Objekt f dem Ergebnis der Dereferenzierung jeden Iterator im Bereich [first, last), in Ordnung. Wenn InputIt eine veränderliche Iterator ist, kann f die Elemente des Bereichs durch die dereferenziert Iterator ändern. Wenn f ein Ergebnis zurückgibt, wird das Ergebnis ignoriert .

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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Parameter

first, last	-	der Bereich um die Funktion zu verarbeiten Original: the range to apply the function to The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
f	-	die einstellige Funktion Objekt angewendet werden Original: the unary function object to be applied 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`.
-`UnaryFunction` must meet the requirements of `MoveConstructible`. Does not have to be `CopyConstructible`

Rückgabewert

f. (bis C + +11)
std::move(f). (seit C++11)

Komplexität

Genau last - first Anwendungen f

Original:

Exactly last - first applications of f

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Mögliche Implementierung

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

Beispiel

Im folgenden Beispiel wird ein Lambda-Funktion um alle Elemente eines Vektors inkrementieren und berechnet dann eine Summe von ihnen:

Original:

The following example uses a Lambda-Funktion 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

Siehe auch


	gilt eine Funktion einer Reihe von Elementen Original: applies a function to a range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Funktions-Template) [edit]

range-for-Schleife	führt eine Schleife über Spektrum (seit C++11) Original: executes loop over range (seit C++11) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. [edit]