类与对象之学生信息管理系统NO.2

​ 经过一个单元的学习，学生信息管理系统迎来了优化！

#include<iostream>
#include<string>
using namespace std;
class student2;
class subject
{
	int score[3];
	const int SMath, SEng, SCpp;
public:
	subject();
	subject(int math, int eng, int cpp);
	void Display() const;
	void Input();
	void Insert();
	void Delete();
	friend class student2;
};

#include "subject.h"
#include<iostream>
#include<string>
using namespace std;
class student2
{
	string name;
	string ID;
	double GPA;
	static int count;
public:
	student2();
	student2(string na, string id);
	string GetName() const;
	void ReckonGPA(const subject& sub);
	double GetGPA() const;
	void Display(const subject& sub) const;
	void Display() const;
	void Input();
	void Insert();
	void Delete();
	static int GetCount();
	friend void OutputStu(const student2* array);

};

#include "subject.h"
subject::subject():SMath(0), SEng(0), SCpp(0)
{
	for(int i=0; i<3; i++)
		score[i] = -1;
}

subject::subject(int math, int eng, int cpp):SMath(0), SEng(0), SCpp(0)
{
	score[0]=math;
	score[1]=eng;
	score[2]=cpp;
}

void subject::Display() const
{
	cout<<"Math "<<" SEng "<<"SCpp "<<endl;
	cout<<SMath<<" "<<SEng<<" "<<SCpp<<endl;
	for(int i=0; i<3; i++)
		cout<<" "<<score[i];
	cout<<endl;
}

void subject::Input()
{
	cout<<"输入成绩："<<endl;
	cout << "输入 数学：";
	cin >> score[0];
	cout << "输入 英语：";
	cin >> score[1];
	cout << "输入 C++：";
	cin >> score[2];
}

void subject::Insert()
{
	if(score[0]<0)
		Input();
}

void subject::Delete()
{
	for(int i=0; i<3; i++)
		score[i]=-1;
}

#include "student2.h"


void student2::Delete()
{
    GPA=-1;
    count--;
}
int student2::count = 0;
int student2::GetCount()
{
    return count;
}

student2::student2()
{
    name = "NULL";
    ID = "NULL";
    GPA = -1;
}

student2::student2(string na, string id)
{
    name = na;
    ID = id;
    GPA = -1;
    count++;
}


string student2::GetName() const
{
    return name;
}

void student2::ReckonGPA(const subject& sub)
{
    GPA = ((sub.score[0] - 60) / 40.0 * sub.SMath * sub.SMath + (sub.score[0]-60)/40.0*sub.SEng*sub.SEng + (sub.score[0]-60)/40.0*sub.SCpp*sub.SCpp);
}

double student2::GetGPA() const
{
    return GPA;
}

void student2::Display(const subject& sub) const
{
    cout << "Name: " << name << endl;
    cout << "ID: " << ID << endl;
    cout<<" Math "<<" SEng "<<" SCpp "<<endl;
    for(int i=0;i<3;i++)
        cout<<sub.score[i]<<" ";
    cout<<endl;
    cout << "GPA: " << GPA << endl;
}

void student2::Display() const
{
    cout << "Name: " << name << endl;
    cout << "ID: " << ID << endl;
}

void student2::Input()
{
    cout << "Enter name: ";
    cin >> name;
    cout << "Enter ID: ";
    cin >> ID;
    count++;
}

void student2::Insert()
{
    if(GPA<0)
        Input();
}

void OutputStu(const student2* array)
{
    cout<<"学生总人数="<<student2::GetCount()<<endl;
    for (int i = 0;i < student2::GetCount();i++)
    {
        if (array[i].GetGPA() != -1)
        {
            cout << "name: "<<array[i].name<<", ID: "<<array[i].ID<<", GPA: "<<array[i].GPA<<endl;
        }
    }
}

#include "student2.h"
const int N = 10;
void menu();
int InputStu(student2* array);
void InputSel(subject* Select, int i);
int SearchStu(const student2* array, string na);
int InsertStu(student2* array);
bool DeleteStu(student2* array,subject* Select, string na);
int main()
{
	student2 array[N];
	subject Select[N];
	int choice, i;
	string name;
	char ch = 'Y';
	do
	{
		menu();
		cin >> choice;
		switch (choice)
		{
		case 1:
			while (ch == 'Y' || ch == 'y')
			{
				i = InputStu(array);
				InputSel(Select, i);
				array[i].ReckonGPA(Select[i]);
				cout << "Do you want to add more students? (Y/N): ";
				cin >> ch;
			}
			break;
		case 2:
			cout << "Enter the name of the student to search:\n ";
			cin >> name;
			int i;
			i = SearchStu(array, name);
			if (i == N)
				cout << "Student not found." << endl;
			else
			{
				array[i].Display(Select[i]);
			}
			break;
		case 3:
			OutputStu(array);
			break;
		case 4:
			i = InsertStu(array);
			if (i)
			{
				cout << "成功插入一条记录\n";
				cout << "录入成绩吗？(Y/N):";
				cin >> ch;
				if (ch == 'Y' || ch == 'y')
				{
					Select[i].Input();
					array[i].ReckonGPA(Select[i]);
				}

			}
			else
				cout << "已达到最大容量，无法插入。\n";
			break;
		case 5:
			cout << "Enter the name of the student to delete:\n ";
			cin >> name;
			if (DeleteStu(array, Select, name))
				cout << "删除成功。\n";
			else
				cout << "删除失败。\n";
			break;
		default:
			cout << "Invalid choice.\n";
			break;

		}
	}while (choice);
	return 0;
}
void menu()
{
	cout << "*********1.录入信息*********\n";
	cout << "*********2.查询信息*********\n";
	cout << "*********3.浏览信息*********\n";
	cout << "*********4.插入信息*********\n";
	cout << "*********5.删除信息*********\n";
	cout << "*********0.退    出*********\n";
}
int InputStu(student2* array)
{
	int i = 0;
	if (student2::GetCount() ==N)
	{
		cout << "已达到最大容量，无法插入。\n";
	}
	else
	{
		while (array[i].GetGPA() > 0)
			i++;
		array[i].Input();
		cout << "录入成功。\n";
	}
	return i;
}
void InputSel(subject* Select, int i)
{
	Select[i].Input();
}
int SearchStu(const student2* array, string na)
{
	int i,j=N;
	for (i = 0; i < N; i++)
	{
		if (array[i].GetGPA() != -1)
		{
			if (array[i].GetName() == na)
			{
				j = i;
				break;
			}
			
		}
	}
	return j;

}

int InsertStu(student2* array)
{
	int i = 0;
	if (student2::GetCount() == N)
	{
		cout << "已达到最大容量，无法插入。\n";
		return 0;
	}
	
	while (array[i].GetGPA() > 0)
		i++;
	array[i].Input();
	return i;
		
}
bool DeleteStu(student2* array, subject* Select, string na)
{
	if (student2::GetCount() == 0)
	{
		cout << "学生信息为空，无法删除。\n";
		return false;
	}
	int i = SearchStu(array, na);
	if (i == N)
	{
		cout << "学生不存在。\n";
		return false;
	}
	array[i].Delete();
	Select[i].Delete();
	return true;
}

*********1.录入信息*********
*********2.查询信息*********
*********3.浏览信息*********
*********4.插入信息*********
*********5.删除信息*********
*********0.退    出*********