c++ - 使用冒泡排序比较类对象

Question

任务:在 OOP 中为一个名为 Student 的类建模，其中包含名称、姓氏和冬季类(class)考试的分数。显示拖欠考试的学生姓名和组内前三名学生。

我在比较分数时遇到了麻烦(前三名学生)。

我的代码:

#define _CRT_SECURE_NO_WARNINGS

#include<iostream>
using namespace std;
#include <string>
#include<stdio.h>

class Student {
private:
    char nume[10];                                                                      
    char prenume[20];
    double matematica;
    double fizica;
    double programare;

public:
    Student(char num[10], char pren[20], double mate, double fiz, double progra);
    void afis();            
    void citire_stud();
    int restanta();
    double media();


};

Student::Student(char num[10] = "", char pren[20] = "", double mate = 0, double fiz = 0, double progra = 0)
{
    strcpy(nume, num);
    strcpy(prenume, pren);
    matematica = mate;
    fizica = fiz;
    programare = progra;
}


void Student::afis()
{
    cout << "Nume: " << nume << endl;
    cout << "Prenume: " << prenume << endl;
    cout << "Nota la matematica: " << matematica << endl;
    cout << "Nota fizica: " << fizica << endl;
    cout << "Nota programare: " << programare << endl;
    cout << endl;

}

void Student::citire_stud()
{
    char num[10];
    char pren[20];
    double mate, fiz, progra;

    cout << "Introduceti numele studentului: " << endl;
    cin >> num;
    strcpy(nume, num);

    cout << "Introduceti preumele studentului: " << endl;
    cin >> pren;
    strcpy(prenume, pren);

    cout << "Introduceti nota la mate studentului: " << endl;
    cin >> mate;
    matematica = mate;

    cout << "Introduceti nota la fizica studentului: " << endl;
    cin >> fiz;
    fizica = fiz;

    cout << "Introduceti nota la programare studentului: " << endl;
    cin >> progra;
    programare = progra;

}

int Student::restanta() //arrears
{
    if (matematica < 5 || programare <5 || fizica < 5)
        return 1;
    else return 0;
}

double Student::media()
{
    double med;
    med = (matematica + fizica + programare) / 3;
        return med;

}

void main()
{
    int cont = 0;
    int res[10];
    int  nr;

    cout << "Cati studenti sunt(max 10): "; //How many students
    cin >> nr;

    Student ob2[10], temp;
    for (int i = 0;i < nr;i++)
    {
        ob2[i].citire_stud();
        if (ob2[i].restanta())
        {

            res[cont++] = i;        
        }

    }
    if (cont == 0)
    {
        cout << "Nu sunt studenti restanti! " << endl;
        goto jmp;
    }
    else
    {
        cout << "\nStundetii restanti sunt: " << endl; 
        int i = 0;
        int k = 0;
        do
        {
            k = res[i];
            ob2[k].afis();
            i++;

        } while (i != cont);    
    }

    jmp:
    cout << "\n\n\n\nStudentii in ordinea medilor sunt: " << endl;

    for (int i = 0;i < nr;i++)
    {

        if (ob2[i].media() < ob2[i + 1].media()) //Not working
        {
            temp = ob2[i];
            ob2[i] = ob2[i + 1];
            ob2[i + 1] = temp;



        }
    }
        for (int i = 0;i < nr;i++)
            ob2[i].afis();


    system("pause");

}

输出:Output

应该是:9 - 7 - 5

Answer 1

你的冒泡排序坏了。 A) 你需要 2 个循环。 B) 你出界了。将其更改为:

for (int j = 0; j < nr; j++)
{
    for (int i = 0;i < nr - 1 ; i++)
    {

        if (ob2[i].media() < ob2[i + 1].media())
        {
            temp = ob2[i];
            ob2[i] = ob2[i + 1];
            ob2[i + 1] = temp;
        }
    }
}