简介

accumulate
fill

accumulate

对指定范围内的元素求和，然后结果再加上一个由val指定的初始值。

• 需要引入include<numeric>

template<class _InIt,
    class _Ty> inline
    _Ty accumulate(_InIt _First, _InIt _Last, _Ty _Val)
    {   // return sum of _Val and all in [_First, _Last)
    return (_STD accumulate(_First, _Last, _Val, plus<>()));
    }

fill

将输入值赋给标志范围内的所有元素。

template<class _FwdIt,
    class _Ty> inline
    void fill(_FwdIt _First, _FwdIt _Last, const _Ty& _Val)
    {   // copy _Val through [_First, _Last)
    _DEBUG_RANGE(_First, _Last);
    _Fill_unchecked(_Unchecked(_First), _Unchecked(_Last), _Val);
    }

示例

#include "stdafx.h"
#include "stdafx.h"
#include "iostream"
#include "string"
#include "algorithm"
#include "vector"
#include "list"
#include <functional>
#include<numeric>
using namespace std;
class Student {
private:
    int number;
    string name;
public:
    Student() {

    }
    Student(int number, string name) {
        cout << "构造 " << number << " " << name.c_str() << endl;
        this->number = number;
        this->name = name;
    }
    Student(const Student & stu) {
        //cout << "copy构造" <<stu.getNumber()<<" "<<stu.getName().c_str()<< endl;
        this->number = stu.getNumber();
        this->name = stu.getName();
    }
    ~Student() {
        //cout<<"析构 " << this->number << " " << this->name.c_str() << endl;
    }

    Student& operator=(const Student& stu) {
        this->number = stu.getNumber();
        this->name = stu.getName();
        return *this;
    }

    void print()const {
        cout << "print 》》 " << this->number << " " << this->name.c_str() << endl;
    }

    int getNumber() const {
        return this->number;
    }
    string getName()const {
        return this->name;
    }
};

void printStuV(vector<Student> v) {
    cout << "开始遍历vector<Student>============" << endl;
    for (vector<Student>::iterator it = v.begin(); it != v.end(); it++) {
        it->print();
    }
    cout << "结束遍历vector<Student>============" << endl;
}
void printNum(vector<int>v) {
    cout << "开始遍历vector<int>============" << endl;
    for (vector<int>::iterator it = v.begin(); it != v.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
    cout << "结束遍历vector<int>============" << endl;
}

struct ReplaceFunc
{
    bool operator()(const Student & stu1) const {
        cout << "ReplaceFunc》》" << endl;
        return stu1.getNumber() >3;
    }
};

int main()
{
    //accumulate示例，需要include<numeric>
    vector<int> vNum;
    vNum.push_back(1);
    vNum.push_back(3);
    vNum.push_back(5);
    int sum = accumulate(vNum.begin(), vNum.end(), 100);
    cout << "accumulate sum " << sum << endl;

    //将输入值赋给标志范围内的所有元素。
    vector<Student> vStu;
    vStu.push_back(Student(1, "one"));
    vStu.push_back(Student(2, "two"));
    vStu.push_back(Student(3, "three"));
    fill(vStu.begin() + 1, vStu.end(), Student(10, "fill"));
    printStuV(vStu);
}

结果：

fill.png