如何在 C++ 中按向量进行升序和降序排序

Posted 2023-02-21

【中文标题】如何在 C++ 中按向量进行升序和降序排序

【英文标题】：How to sort ascending and descending order by vectors in C++

【发布时间】：2015-05-10 16:44:37

【问题描述】：

我正在尝试编写煎饼吃者的 C++ 代码。我输入了 7 个人吃的煎饼的数量。我找到了最大值。和分钟。食客，但我无法按人们吃的煎饼数量对它们进行分类。有人可以帮我吗？

谢谢。

#include <iostream>
#include <string>
#include <vector>
#include <sstream>

using std::cout;
using std::cin;
using std::endl;
using std::vector;
using std::string;

struct Person

    string name;
    unsigned int pancakesAte;
;

int main()

    const int NUM_PEOPLE = 7;
    vector<Person> people;
    unsigned int mostPancakesIndex = 0;
    unsigned int leastPancakesIndex = 0;
    for(int index = 0; index < NUM_PEOPLE; index++)
    
        std::stringstream ss;  
        Person person;  
        ss << "Person " << index; 
        person.name = ss.str();  
        cout << "how many did person " << person.name << " eat? ";
        cin >> person.pancakesAte;
        people.push_back(person);
        if ( person.pancakesAte > people[mostPancakesIndex].pancakesAte )
            mostPancakesIndex = index;                                   
            if ( person.pancakesAte < people[leastPancakesIndex].pancakesAte )
            leastPancakesIndex = index; 
    

    std::vector<Person>::iterator iter = people.begin();
    while (iter != people.end())
    
        cout << iter->name << " ate " << iter->pancakesAte << " pancakes." << endl;
        ++iter;
    
    cout << people[mostPancakesIndex].name << " ate the most pancakes - he/she ate " << people[mostPancakesIndex].pancakesAte << " pancakes." << endl;
    cout << people[leastPancakesIndex].name << " ate the least pancakes - he/she ate " << people[leastPancakesIndex].pancakesAte << " pancakes." << endl;
**strong text**

强文本

【问题讨论】：

你不需要排序，std::minmax_element 应该做你需要的。

İ如果您运行代码，它会打印每个人吃了多少煎饼，但是当我打印它们时，我想按煎饼编号对它们进行排序，然后再次打印。

【参考方案1】：

上次我使用std::sort，您可以将比较函数传递给std::sort。因此，如果你想要一个降序排序，你传递一个降序比较函数。如果你想按偶数煎饼排序，你可以写一个函数来做到这一点。

函数很容易写：

bool Comparison(const Type& a, const Type& b)

  // if you want a to come before b
  // in the ordering, return true.
  return // true or false

排序被调用：

std::sort(your_vector.begin(), your_vector.end(),
          Comparison); // Your ordering function.