简单题！请问c++的struct怎么改成class

#include<iostream>
#include<string>
using namespace std;
struct Student
{
    string number;
    string name;
    double grade;
    void functionZero()
    {
        int a;
        string b;
        string c;
        for (int i = 0; i < 11; i++)
        {
            cout << "请输入第" << i << "个同学的学号" << endl;
            cin >> b;
            stu[i].number = b;
            cout << "请输入第" << i << "个同学的姓名" << endl;
            cin >> c;
            stu[i].name = c;
            cout << "请输入" << stu[i].number << stu[i].name << "的成绩" << endl;
            cin >> a;
            if (a >= 0)
            {
                stu[i].grade = a;
            }
            else
            {
                cout << "成绩不能为负数" << endl;
            }
        }
    }

    void functionOne()
    {

        int a = 0;
        cout << "不及格学生名单" << endl;
        for (int i = 0; i < 10; i++)
        {
            if (stu[i].grade < 60)
            {
                cout << "学号" << stu[i].number << "姓名" << stu[i].name << "成绩" << stu[i].grade << endl;
                a++;
            }
        }
        cout << "不及格学生人数：" << a << endl;
    }
    void functionTwo()
    {
        int student[6] = { 0 };
        cout << "各分数段的学生人数名单" << endl;
        for (int i = 0; i < 10; i++)
        {
            
            if (stu[i].grade < 60)
            {
                student[0]++;
            }
            else if (60<=stu[i].grade&& stu[i].grade<70)
            {
                student[1]++;
            }
            else if (70 <= stu[i].grade&&stu[i].grade < 80)
            {
                student[2]++;
            }
            else if (80 <= stu[i].grade&&stu[i].grade < 90)
            {
                student[3]++;
            }
            else if (90 <= stu[i].grade&&stu[i].grade < 99)
            {
                student[4]++;
            }
            else if (stu[i].grade == 100)
            {
                student[5]++;
            }
        }
        cout << "第0段人数：" << student[0] << "所占百分比：" << student[0] << "0%" << endl;
        cout << "第1段人数：" << student[1] << "所占百分比：" << student[1] << "0%" << endl;
        cout << "第2段人数：" << student[2] << "所占百分比：" << student[2] << "0%" << endl;
        cout << "第3段人数：" << student[3] << "所占百分比：" << student[3] << "0%" << endl;
        cout << "第4段人数：" << student[4] << "所占百分比：" << student[4] << "0%" << endl;
        cout << "第5段人数：" << student[5] << "所占百分比：" << student[5] << "0%" << endl;
    }
}stu[10];


int main()
{
    Student p;
    struct Student stu[10];
    p.functionZero();
    cout << "^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" << endl;
    cout << "                         学生成绩统计                   " << endl;
    cout << "退出程序                                      使用请按0" << endl;
    cout << "统计不及格人数并打印不及格学生名单            使用请按1 " << endl;
    cout << "统计各分数段的学生人数及所占的百分比          使用请按2 " << endl;
    cout << "^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" << endl;
    while (1)
    {
        int x;
        cout << "请输入序号" << endl;
        cin >> x;
        if (x == 0)
        {
            return 0;
        }
        else if (x == 1)
        {
            p.functionOne();
        }
        else if (x == 2)
        {
            p.functionTwo();
        }
        else
        {
            cout << "输入有误" << endl;
        }
        return 0;
    }
}

struct Student
{

改为

class Student
{
public:

再参考这个改下，

class Student
{
    public:
    void functionZero() {***}

改成

class Student
{
    public:
    void functionZero();
}stu[10];

void Student::functionZero()
{
***
}

struct可以直接改成class
struct 和 class的区别是，struct中的变量和方法默认都是public类型，而class的变量和方法默认为private类型