std::accumulate
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Defined in header <numeric> | ||
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.
目次 |
[編集]パラメータ
| first, last | - | 和への要素の範囲 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&. |
| 型の要件 | ||
-InputIt は InputIteratorの要求を満足しなければなりません。 | ||
-T は CopyAssignable and CopyConstructible。 | ||
[編集]値を返します
The sum of the given value and elements in the given range.
[編集]可能な実装
| First version |
|---|
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;} |
[編集]例
#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';}
出力:
55 3628800 sssssbbbbb
[編集]参照
範囲内の隣接する要素間の差を計算します 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. (関数テンプレート) | |
要素の2つの範囲の内積を計算します 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. (関数テンプレート) | |
要素の範囲の部分和を計算します 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. (関数テンプレート) | |
