欢迎找来bug

#include<iostream>
#include<string>
#include<vector>
using namespace std;
struct my_student
{
protected:
	string name = "张三";
	int student_number = 100000;
	int score = 60;
public:
	my_student(string nm, int st_n, int sc)
	{
		name = nm;
		student_number = st_n;
		score = sc;
	}
	string get_name()
	{
		return name;
	}
	void set_name(string nm)
	{
		name = nm;
	}
	int get_student_number()
	{
		return student_number;
	}
	void set_student_number(int st_n)
	{
		if (st_n >= 100000 && st_n < 1000000)
		{
			student_number = st_n;
		}
	}
	int get_score()
	{
		return score;
	}
	bool set_score(int sc)
	{
		if(sc >= 0 && sc <= 100)
		{
			score = sc;
			return 1;
		}
		return 0;
	}
};
struct my_class
{
private:
	vector<my_student>cl;
public:
	my_student get_student(int num)
	{
		return cl[num - 1];
	}
	bool set_student(int num, my_student stu)
	{
		if(stu.get_score() >= 0 && stu.get_score() <= 100 && stu.get_student_number() >= 100000 && stu.get_student_number() <= 1000000)
		{
			cl[num - 1] = stu;
			return 1;
		}
		return 0;
	}
	vector<my_student> get_class()
	{
		return cl;
	}
	void delete_student(int num)
	{
		cl.erase(cl.begin() + num - 1);
	}
	bool add_student(my_student stu)
	{
		if(stu.get_score() >= 0 && stu.get_score() <= 100 && stu.get_student_number() >= 100000 && stu.get_student_number() <= 1000000)
		{
			cl.push_back(stu);
			return 1;
		}
		return 0;
	}
	int find_student(my_student stu)
	{
		for (unsigned int i = 0; i < cl.size(); i++)
		{
			if (cl[i].get_score() == stu.get_score() && cl[i].get_name() == stu.get_name() && cl[i].get_student_number() == stu.get_student_number())
			{
				return i + 1;
			}
		}
		return -1;
	}
	void clear_class()
	{
		cl.clear();
	}
};
void show_menu()
{
	system("cls");
	cout << "________________________\n";
	cout << "|                      |\n";
	cout << "|  欢迎来到班级管理器  |\n";
	cout << "|       功能如下       |\n";
	cout << "|     1、显示学生      |\n";
	cout << "|     2、添加学生      |\n";
	cout << "|     3、删除学生      |\n";
	cout << "|     4、查找学生      |\n";
	cout << "|     5、清空班级      |\n";
	cout << "|     0、退出系统      |\n";
	cout << "|- - - - - - - - - - - |\n";
	cout << "|       开始体验       |\n";
	cout << "|                      |\n";
	cout << "|         附劵         |\n";
	cout << "|     自行撕开无效     |\n";
	cout << "________________________\n";
	cout << "请输入功能码:";
}
int main()
{
	my_class c;
	int x;
	while (1)
	{
		show_menu();
		cin >> x;
		switch(x)
		{
		case 1:
		{
			if (c.get_class().empty())
			{
				cout << "班级为空\n";
				system("pause");
			}
			else
			{
				vector<my_student> students = c.get_class();
				unsigned int size_ = students.size();
				
				for (unsigned int i = 0; i < size_; i++)
				{
					cout << i+1 << "号学生\t姓名:" << students[i].get_name() << "\t学号:" << students[i].get_student_number() << "\t分数:" << students[i].get_score() << '\n';
				}
				system("pause");
			}
			break;
		}
		case 2:
			{
				string name;
				int student_num;
				int score;
				cout << "请输入要添加的学生的姓名:";
				cin >> name;
				cout << "\n请输入要添加的学生的学号:";
				cin >> student_num;
				while(student_num < 100000 || student_num > 1000000)
				{
					cout << "学号必须是六位数\n请重新输入:";
					cin >> student_num;
				}
				cout << "\n请输入要添加的学生的分数:";
				cin >> score;
				while(score < 0 || score > 100)
				{
					cout << "分数要在0~100之间\n请重新输入:";
					cin >> score;
				}
				cout << '\n';
				c.add_student({name, student_num, score});
				system("pause");
				break;
			}
		case 3:
			{
				int num;
				cout << "请输入要删除第几个学生:";
				cin >> num;
				c.delete_student(num);
				system("pause");
				break;
			}
		case 4:
			{
				string name;
				int student_num, score;
				cout << "请输入要查找的学生的姓名:";
				cin >> name;
				cout << "\n请输入要查找的学生的学号:";
				cin >> student_num;
				cout << "\n请输入要查找的学生的分数:";
				cin >> score;
				if (c.find_student({name, student_num, score}) == -1)
				{
					cout << "查无此人\n";
				}
				else
				{
					cout << c.find_student({name, student_num, score}) << '\n';
				}
				system("pause");
				break;
			}
		case 5:
			{
				c.clear_class();
				break;
			}
		case 0:
			{
				return 0;
			}
		default:
			{
				cout << "输入错误!";
				system("pause");
				break;
			}
		}
	}
}

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前提是……
告诉我有什么可以改进的地方

求你了