它是用于执行加法的Function对象。对象类的调用返回其两个参数相加的结果(由operator +返回)。
用法:
template struct plus:binary_function
{
T operator() (const T& x, const T& y) const { return x + y; }
};
模板参数：
T - Type of the arguments and return type of the functional call.
The type shall support the operation (operator+).
成员类型：
x:Type of the first argument in member operator()
y:Type of the second argument in member operator()
result_type:Type returned by member operator()
// C++ program to illustrate std::plus
// by adding the respective elements of 2 arrays
#include <iostream> // std::cout
#include <functional> // std::plus
#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::plus to the whole array
std::transform(first, first + 5, second, results, std::plus<int>());
// Printing the result array
for (int i = 0; i < 5; i++)
std::cout << results[i] << " ";
return 0;
}输出：
11 22 33 44 55
另一个例子：
// C++ program to illustrate std::plus
// by adding all array elements with a number
#include <bits/stdc++.h>
int main()
{
// Array with elements to be added
int arr[] = { 10, 20, 30 };
// size of array
int size = sizeof(arr) / sizeof(arr[0]);
// Variable with which array is to be added
int num = 100;
// Variable to store result
int result;
// using std::accumulate to perform addition on array with num
// using std::plus
result = std::accumulate(arr, arr + size, num, std::plus<int>());
// Printing the result
std::cout << "The result of 100 + 10 + 20 + 30 is " << result;
return 0;
}输出：
The result of 100 + 10 + 20 + 30 is 160
相关用法
注：本文由纯净天空筛选整理自 std::plus in c++。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。