std::accumulate
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| definiert in Header <numeric>
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| template< class InputIt, class T > T accumulate( InputIt first, InputIt last, T init ); |
(1) | |
| template< class InputIt, class T, class BinaryOperation > T accumulate( InputIt first, InputIt last, T init, |
(2) | |
Computes the sum of the given value init and the elements in the range [first, last). The first version uses operator+ to sum up the elements, the second version uses the given binary function op.
Inhaltsverzeichnis |
[Bearbeiten] Parameter
| first, last | - | das Spektrum der Elemente Summe
Original: the range of elements to sum The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| init | - | initial value of the sum |
| op | - | binary operation function object that will be applied. The signature of the function should be equivalent to the following: Ret fun(const Type1 &a, const Type2 &b); The signature does not need to have const &. |
| Type requirements | ||
-InputIt must meet the requirements of InputIterator.
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-T must meet the requirements of CopyAssignable and CopyConstructible.
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[Bearbeiten] Rückgabewert
The sum of the given value and elements in the given range.
[Bearbeiten] Mögliche Implementierung
| First version |
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template<class InputIt, class T> T accumulate(InputIt first, InputIt last, T value) { for (; first != last; ++first) { value = value + *first; } return value; } |
| Second version |
template<class InputIt, class T, class BinaryOperation> T accumulate(InputIt first, InputIt last, T value, BinaryOperation op) { for (; first != last; ++first) { value = op(value, *first); } return value; } |
[Bearbeiten] Beispiel
#include <iostream> #include <vector> #include <numeric> #include <string> int multiply(int x, int y) { return x*y; } std::string magic_function(std::string res, int x) { return res += (x > 5) ? "b" : "s"; } int main() { std::vector<int> v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; int sum = std::accumulate(v.begin(), v.end(), 0); int product = std::accumulate(v.begin(), v.end(), 1, multiply); std::string magic = std::accumulate(v.begin(), v.end(), std::string(), magic_function); std::cout << sum << '\n' << product << '\n' << magic << '\n'; }
Output:
55 3628800 sssssbbbbb
[Bearbeiten] Siehe auch
| berechnet die Differenzen zwischen benachbarten Elementen in einer Reihe Original: computes the differences between adjacent elements in a range The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Funktions-Template) | |
| berechnet das innere Produkt von zwei Bereichen der Elemente Original: computes the inner product of two ranges 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) | |
| berechnet die Teilsumme von einer Reihe von Elementen Original: computes the partial sum of 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) | |
