如何在不更改原始数组的情况下对指向结构的指针数组进行排序

How do I sort array of pointers to structs without changing original array?

本文关键字：数组 结构 指针 排序 情况下 原始      更新时间：2023-10-16

我对C++和指针还很陌生，非常感谢您的帮助。我正在尝试打印一个已排序的指针数组，而不更改原始的结构数组。我无法正确地对指针进行排序。我使用的是对原始数组有效的std：：排序，但在指针上使用它失败了。更糟糕的是，我失败的尝试都改变了原来的样子。谢谢你抽出时间。

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <string.h>
using namespace std;
struct Student
{
    int age;
    char name[30];
};
void displayStudent(Student s)
{
    cout << endl<< s.age<< "    "<< s.name;
}

int main()
{
    Student s1;
    s1.age = 10;
    strcpy(s1.name, "Guy");
    Student s2;
    s2.age = 33;
    strcpy(s2.name, "Buddy");
    Student s3;
    s3.age = 16;
    strcpy(s3.name, "Friend");
    Student s4;
    s4.age = 55;
    strcpy(s4.name, "Pal");
    Student myClass[4];
    myClass[0] = s1;
    myClass[1] = s2;
    myClass[2] = s3;
    myClass[3] = s4;
    Student *myClassPt;
    myClassPt = &myClass[0];
    Student *SBN[4];
    Student *SBG[4];
    Student *SBA[4];
    for (int i = 0; i < 4; i++)
    {
        SBN[i] = &(myClassPt[i]);
        SBA[i] = &(myClassPt[i]);
    }
    cout << "Original" << endl;
    for (int i = 0; i < 4; i++)
    {
        displayStudent(myClass[i]);
    }
    std::sort(*SBN, *SBN + 4, [](Student  &a, Student  &b){ return a.name < b.name; });
    std::sort(*SBA, *SBA + 3, [](Student const &a, Student const &b){ return a.age < b.age; });
    cout <<endl<<endl<< "Sorted by name" << endl;
    for (int i = 0; i < 4; i++)
    {
        displayStudent(*SBN[i]);
    }
    cout << endl << endl << "Sorted by age" << endl;
    for (int i = 0; i < 4; i++)
    {
        displayStudent(*SBA[i]);
    }
    cout << endl <<endl<< "Original" << endl;
    for (int i = 0; i < 4; i++)
    {
        displayStudent(myClass[i]);
    }
    return 0;
}

似乎你想根据指针所指向的对象对指针进行排序。因此，你需要根据指针所指的对象对它们进行排序，而不是试图直接对它们所指向的物体进行排序：

std::sort(SBN, SBN + 4, [](const Student* a, const Student* b)
                        { return a->name < b->name; });

下面是一个工作示例：

#include <iostream>
#include <algorithm>
struct student { int age; };
int main()
{
  student ss[] = { {23}, {12}, {42}, {9}};
  std::cout << "studentsn";
  for (const auto& s : ss) std::cout << s.age << " ";
  std::cout << std::endl;
  student* ps[] = { &ss[0], &ss[1], &ss[2], &ss[3]};
  std::cout << "pointers to studentn";
  for (auto p : ps) std::cout << p->age << " ";
  std::cout << std::endl;
  std::sort(ps, ps + 4, [](const student* a, const student* b)
                        { return a->age < b->age;});
  std::cout << "pointers to student after sortingn";
  for (auto p : ps) std::cout << p->age << " ";
  std::cout << std::endl;
}

输出：

students
23 12 42 9 
pointers to student
23 12 42 9 
pointers to student after sorting
9 12 23 42
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