[C++] 이중 링크드 리스트(Doubly Linked List)로 학생 관리 프로그램 만들기

#include <iostream>
#include <string>

using namespace std;

struct student
{
	int id;
	string name;
	student* next;
	student* prev;
};

class studentBook
{
private:
	student* head;
	student* tail;

public:
	studentBook();
	~studentBook();
	void insert(int id, string name);
	void remove(int id);
	void print();
	void print_reverse();
	void search(int id);
};

int main()
{
	int num = 0;
	int ID = 0;
	string name = "";

	studentBook studentRecord;

	while (true)
	{
		cout << "1.삽입 2.출력 3.역순출력 4.검색 5.삭제 6.종료" << endl;
		cout << "번호를 입력하세요 : ";
		cin >> num;
		cout << "\n";

		switch (num)
		{
		case 1:
			cout << "학번 : "; cin >> ID;
			cout << "이름 : "; cin >> name;
			cout << endl;
			studentRecord.insert(ID, name);
			break;
		case 2:
			studentRecord.print();
			break;
		case 3:
			studentRecord.print_reverse();
			break;
		case 4:
			cout << "찾을 학생의 학번을 입력하시오.\n";
			cout << "학번 : "; cin >> ID;
			cout << endl;
			studentRecord.search(ID);
			break;
		case 5:
			cout << "삭제할 학생의 학번을 입력하시오.\n";
			cout << "학번 : "; cin >> ID;
			studentRecord.remove(ID);
			break;
		case 6:
			return 0;
		default:
			cout << "잘못된 번호입니다. 다시 입력해주세요.\n\n";
			break;
		}
	}
}

studentBook::studentBook()
{
	head = nullptr;
	tail = nullptr;
}

studentBook::~studentBook()
{
	student* current = head;
	while (current != nullptr)
	{
		student* next = current->next;
		delete current;
		current = next;
	}
}

void studentBook::insert(int id, string name)
{
	student* newStudent = new student{ id, name, nullptr, nullptr };

	if (head == nullptr)
	{
		head = newStudent;
		tail = newStudent;
	}
	else		// 리스트에 노드가 있을 경우
	{
		tail->next = newStudent;
		newStudent->prev = tail;
		tail = newStudent;
	}
	cout << "학생이 추가되었습니다.\n";
}

void studentBook::remove(int id)
{
	if (head == nullptr)
	{
		cout << "등록된 학생이 없습니다.\n\n";
		return;
	}

	student* current = head;
	
	// 삭제할 노드 탐색
	while (current != nullptr && current->id != id)
	{
		current = current->next;
	}

	// 노드를 찾지 못한 경우
	if (current == nullptr)
	{
		cout << "해당 학번의 학생을 찾을 수 없습니다.\n\n";
		return;
	}

	// --- 노드 연결 끊기 ---
	if (current == head)
	{
		head = current->next;
		if (head != nullptr)
		{
			head->prev = nullptr;
		}
		else
		{
			tail = nullptr;
		}
	}
	else if (current == tail)
	{
		tail = current->prev;
		tail->next = nullptr;
	}
	else
	{
		current->prev->next = current->next;
		current->next->prev = current->prev;
	}

	delete current;
	cout << "학생이 삭제되었습니다.\n\n";
}

void studentBook::print()
{
	if (head == nullptr)
	{
		cout << "등록된 학생이 없습니다.\n\n";
		return;
	}

	student* current = head;
	while (current != nullptr)
	{
		cout << "학번 : " << current->id << ", 이름 : " << current->name << endl;
		current = current->next;
	}
	cout << endl;
}

void studentBook::print_reverse()
{
	if (tail == nullptr)
	{
		cout << "등록된 학생이 없습니다.\n\n";
		return;
	}

	cout << "--- 역순 출력 ---\n";
	student* current = tail;
	while (current != nullptr)
	{
		cout << "학번 : " << current->id << ", 이름 : " << current->name << endl;
		current = current->prev;
	}
	cout << endl;
}

void studentBook::search(int id)
{
	if (head == nullptr)
	{
		cout << "등록된 학생이 없습니다.\n\n";
		return;
	}

	student* current = head;
	while (current != nullptr)
	{
		if (current->id == id)
		{
			cout << "학생을 찾았습니다.\n";
			cout << "학번 : " << current->id << "\n이름 : " << current->name << "\n\n";
			return;
 	}
		current = current->next;
	}
	cout << "해당 학번의 학생을 찾을 수 없습니다.\n\n"; 
}