第15周程序阅读3

最新推荐文章于 2021-01-23 14:47:36 发布

原创最新推荐文章于 2021-01-23 14:47:36 发布 · 283 阅读

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本文介绍了C++ STL中四个重要的数值算法：accumulate、partial_sum、adjacent_difference 和 inner_product。这些算法均包含在<numeric>头文件中，通过实例演示了它们的功能及用法。

#include <algorithm>
#include <functional>
#include <vector>
#include <iostream>
#include <numeric>
#include <iterator>
using namespace std;
int main()
{
    int a[] = {1,4,7,2,5,8};
    int b[] = {1,2,3,3,2,1};
    const int ASZ = sizeof a / sizeof a[0];
    const int BSZ = sizeof b / sizeof b[0];
    ostream_iterator<int> out(cout,"  ");
    copy(a, a + ASZ, out);
    cout<<endl;
    copy(b, b + BSZ, out);
    cout<<endl;
    int r = accumulate(a, a + ASZ, 0);
    cout << "accumulate 1: " << r << endl;
    // Should produce the same result:
    r = accumulate(b, b + BSZ, 0, plus<int>());
    cout << "accumulate 2: " << r << endl;
    r = inner_product(a, a + ASZ, b, 0);
    // 或  r = inner_product(a, a + ASZ, b, 0, plus<int>(), multiplies<int>());
    cout << "inner_product : " << r << endl;
    int* it = partial_sum(a, a + ASZ, b);
    // 或 int* it = partial_sum(a, a + ASZ, b, plus<int>());
    copy(b, it, out);
    cout<<endl;
    it = adjacent_difference(a, a + ASZ, b);
    // 或 it = adjacent_difference(a, a + ASZ, b, minus<int>());
    copy(b, it, out);
    cout<<endl;
    return 0;
}

运行结果：