学步园

template <class InputIterator1, class InputIterator2, class T>
   T inner_product (InputIterator1 first1, InputIterator1 last1,
                    InputIterator2 first2, T init);

template <class InputIterator1, class InputIterator2, class T,
          class BinaryOperation1, class BinaryOperation2>
   T inner_product (InputIterator1 first1, InputIterator1 last1,
                    InputIterator2 first2, T init,
                    BinaryOperation1 binary_op1,
                    BinaryOperation2 binary_op2);

inner_product 通过初始化具有 Init
的 累加器 acc 然后进行修改其计算结果为: acc = acc + (*i1) * (*i2) - 或 - acc = Binary_Op1(acc， Binary_Op2(*i1，
*i2)对范围 [First， Last) 的每在范围 [First2， First2 的迭代器 i1和迭代器 i2+
(Last - First)按顺序。

#include "algostuff.hpp"

#include <numeric>
#include <iterator>
#include <ostream>

using namespace std;

int main(){
list<int> coll;
INSERT_ELEMENTS(coll,1,6);
PRINT_ELEMENTS(coll);

//（0+1×1 +2×2 +3×3+4×4+5*5+6*6)

cout<<"inner reverse product:"<<inner_product(coll.begin(),coll.end(),coll.begin(),0)<<endl;

//（0+1×6 +2×5+3×4+4×3+5*2+6*1)
cout<<"inner reverse product:"<<inner_product(coll.begin(),coll.end(),coll.rbegin(),0)<<endl;

//（1* 1+1 * 2+2 * 3+3 * 4+4 * 5+5 * 6+6)
cout<<"product of sums:"<<inner_product(coll.begin(),coll.end(),coll.begin(),1,multiplies<int>(),plus<int>())<<endl;

return 0;

}

编译后输出：

 1 2 3 4 5 6 inner reverse product:91
inner reverse product:56
product of sums:46080