std::multiplies 是乘法的二元函数对象。

常被用于 std::transform 或者 std::accumulate 等的运算算子。
例子一.实现两个数组元素的相乘

// C++ program to illustrate std::multiplies 
// by multiplying the respective elements of 2 arrays 
#include <iostream> // std::cout 
#include <functional> // std::multiplies 
#include <algorithm> // std::transform 
int main() 
    // First array 
    int first[] = { 1, 2, 3, 4, 5 }; 
    // Second array 
    int second[] = { 10, 20, 30, 40, 50 }; 
    // Result array 
    int results[5]; 
    // std::transform applies std::multiplies to the whole array 
    std::transform(first, first + 5, second, results, std::multiplies<int>()); 
    // Printing the result array 
    for (int i = 0; i < 5; i++) 
        std::cout << results[i] << " "; 
    return 0; 
//output:10 40 90 160 250
例子二.实现多个数字的累乘
 
#include <bits/stdc++.h> 
int main() 
    // Array with elements to be multiplying 
    int arr[] = { 10, 20, 30 }; 
    // size of array 
    int size = sizeof(arr) / sizeof(arr[0]); 
    // Variable with which array is to be multiplied 
    int num = 10; 
    // Variable to store result 
    int result; 
    // using std::accumulate to perform multiplication on array with num 
    // using std::multiplies 
    result = std::accumulate(arr, arr + size, num, std::multiplies<int>()); 
    // Printing the result 
    std::cout << "The result of 10 * 10 * 20 * 30 is " << result; 
    return 0; 
//output:The result of 10 * 10 * 20 * 30 is 60000
例子三.两个vector数组元素相乘
 
#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
int main()
    std::vector<int> v1 = {10, 20, 30, 40, 50};
    std::vector<int> v2 = { 1, 2, 3, 4, 5 };
    std::vector<int> result(5);
    std::transform(v1.begin(), v1.end(), v2.begin(), result.begin(), std::multiplies<int>());
    for (int i : result) {
        std::cout << i << "\t";
    std::cout << std::endl;
    return 0;
                                    <br />#include <iostream><br />#include <string><br />#include <vector><br />#include <iterator><br />#include <algorithm><br />#include <list><br />#include <set><br />#include <cstdlib><br />#include <functional><br />#include <numeric><br />using namesp
                                    但用普通的计算器无法完成计算，于是他请编程班的贝贝帮忙设计一个“超级计算器”，解决他所遇到的问题。贝贝是学校信息学编程小组的学生，一天，他的数学老师碰到这样一个问题：他想求。请你编一程序，帮贝贝解决这个问题。两行，分别是两个在10。
template <class T> struct multiplies {
  T operator() (const T& x, const T& y) const {return x*y;}
  typedef T first_argument_type;
  typedef T second_argument_type;
                                    accumulate(A,A+N,num,multiplies<int>))  //数组累乘 ，再和n相乘
accumulate(A, A + N, num);            //数组累加 ，再和n相加
别忘了把头文件 #include<numeric>包含进来
#include<iostream>
#incl...