學生管理系統-C++版

今天下午有個面試，但是不想複習，就將寫好的這個簡單學生關係系統發佈出來。
另：祝願自己面試順利，加油！

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本篇涉及到的知識點：
1、單鏈表的遍歷、插入、刪除
2、switch分支處理鍵盤輸入
3、類外實現、多文件編程
4、ofstream操作文件、寫文件

• ofstream打開文件
  • 使用對象打開文件 outfile.open(“student.txt”, ios::out || ios::app);
  • 默認方式打開文件 ofstream out(“student.txt”);
  • 參數如下
    
• 關閉文件 outfile.close();

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說明：
1、Student類中有學號、姓名、分數三個公有成員，私有成員next用於組織鏈表
2、系統的功能：

• 錄入學生信息（學生信息以鏈表形式存儲）
• 修改學生信息
• 刪除學生信息（鏈表刪除節點）
• 查看學生信息
• 將全部的學生信息寫入student.txt文件（遍歷鏈表，寫入文件）
• 根據學生成績排名（對鏈表節點排序，已經更新實現）
  • 單鏈表的排序一般針對帶頭節點的而言（交換節點、交換數據域）
  • 本篇採用了一個交換節點的方法實現
  • 單鏈表排序、逆置以後可能會在某一個小項目中具體再討論

3|、代碼中可能會缺少註釋，有時間再補上。

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student.h

#ifndef _STUDENT_H_
#define _STUDENT_H_

class Student{
public:
	/*******構造***********/
	Student(char* num, char* name, float score);
	Student();
	
	char stu_num[15];
	char stu_name[30];
	float stu_score;
	
	void afterInsert(Student* p);	//後插
	void afterDelete(); //後刪
	Student* getNext();

	/*******查詢學生信息**********/
	void getMesg();
	/*******修改學生信息**********/
	void changeMesg(int n,char* ptr);
	void changeGrade(float  f);

private:
	Student* next;
};
#endif

student.cpp(負責類外實現)

#define  _CRT_SECURE_NO_WARNINGS
#include "student.h"
#include <cstring>
#include <iostream>
using namespace std;

Student::Student(){
	strcpy(this->stu_num, "");
	strcpy(this->stu_name, "");
	this->stu_score = 0;
	this->next = NULL;
}
Student::Student(char* num, char* name, float score){
	strcpy(this->stu_num, num);
	strcpy(this->stu_name, name);
	this->stu_score = score;
	this->next = NULL;
}

void Student::afterInsert(Student* p){	//後插
	p->next = this->next;
	this->next = p;
}
void Student::afterDelete(){ //後刪
	Student* pTmp = this->next;
	this->next = pTmp->next;
	delete pTmp;

}
Student* Student::getNext(){
	return this->next;
}

void Student::getMesg(){
	cout << "學號：" << stu_num << "  姓名" << stu_name << "  成績" << stu_score<<endl;
}

void Student::changeMesg(int n, char* ptr){
	switch (n)
	{
	case 1:
		strcpy(stu_num, ptr);
		break;
	case 2:
		strcpy(stu_name, ptr);
		break;;
	default:
		break;
	}
}
void Student::changeGrade(float  f){
	this->stu_score = f;
}

主函數main（主菜單、構建鏈表、查詢學生、修改信息、刪除學生）

#define  _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <fstream>
#include "student.h"


using namespace std;


//建立鏈表函數（創建學生）
void creatList(Student* stu){
	Student* p = new Student;
	char str[30];//學號或者姓名
	float score;//分數
	cout << "輸入學號：";
	cin >> str;
	p->changeMesg(1, str);
	memset(str, 0, sizeof(str));//清空str


	cout << "輸入姓名：";
	cin >> str;
	p->changeMesg(2, str);
	memset(str, 0, sizeof(str));//清空str

	cout << "輸入得分：";
	cin >> score;
	p->changeGrade(score);

	system("cls");
	cout << "信息輸入完成!" << endl;

	while (stu->getNext())		//尋找尾節點
		stu = stu->getNext();

	stu->afterInsert(p);

	//TODO...文件處理
}

//學生信息查詢
Student* findMesg(Student* stu){
loop:
	cout << "1、按姓名查詢\t2、按學號查詢\tq、返回上一級菜單" << endl;
	char p[5], ptr[30];
	Student* pCur = stu;
	cin >> p;
	if (p[0] != '1' && p[0] != '2' && p[0] != 'q' || strlen(p) > 1){
		cout << "您的輸入有誤，重新輸入" << endl;
		goto loop;
	}
	switch (p[0]){
	case '1':
		cout << "輸入要查找的姓名：";
		cin >> ptr;
		for (; strcmp(ptr, pCur->stu_name) != 0;){
			if (pCur->getNext() == NULL){
				cout << "對不起，您要查找的人不存在！" << endl;
				goto loop;
			}
			pCur = pCur->getNext();
		}

		return pCur;
	case '2':
		cout << "輸入要查找的學號：";
		cin >> ptr;
		for (; strcmp(ptr, pCur->stu_num) != 0;){
			if (pCur->getNext() == NULL){
				cout << "對不起，您要查找的學號不存在！" << endl;
				goto loop;
			}
			pCur = pCur->getNext();
		}

		return pCur;
	case 'q':
		system("cls");
		cout << "您的輸入有誤,請重新輸入!" << endl;
		goto loop;
	}
}
//刪除鏈表節點
void delList(Student* stu){
	Student* p = NULL;
	char selet[4];
	//system("cls");
	cout << "刪除前，會根據您的提示找到您要刪除的學生信息" << endl;
	p = findMesg(stu);
	if (p != NULL){
		cout << "確認刪除嗎?(yes/任意鍵返回)" << endl;
		cin >> selet;
		if (strcmp(selet, "yes") == 0){
			for (; stu->getNext() != p;){
				stu = stu->getNext();
			}
			stu->afterDelete();
			cout << "該學生信息刪除成功!" << endl;
		}

	}
}

//修改節點信息
void changeInfo(Student* stu){
	system("cls");
	cout << "修改前，會根據您提供的信息查找到您要修改的信息" << endl;
	Student* p = NULL;

	float score;
	p = findMesg(stu);
	if (p != NULL){
		cout << "請輸入成績" << endl;
		cin >> score;
		p->changeGrade(score);
		cout << "修改成功" << endl;
	}
}
void putStu(Student* stu){
	system("cls");
	cout << "1、查看指定學生信息\t2、查看所有學生信息\t3、分段輸出學生信息" << endl;
	char ch;
	int n = 0;

	stu = stu->getNext();
	cin >> ch;
	switch (ch){
	case '1':
		stu = findMesg(stu);
		if (stu == NULL){
			break;
		}
		stu->getMesg();
		break;
	case'2':
		while (stu){
			stu->getMesg();
			stu = stu->getNext();
		}
		break;
	case'3':
		cout << "a-60分以下；b-60~70分之間；c-70~80分之間；d-80~90分之間；e-90~100分之間：" << endl;
		cin >> ch;
		switch (ch){
		case'a':
			while (stu){
				if (stu->stu_score <= 60){
					stu->getMesg();
					++n;
				}
				stu = stu->getNext();
			}
			break;
		case'b':
			while (stu){
				if (stu->stu_score > 60 && stu->stu_score <= 70){
					stu->getMesg();
					++n;
				}
				stu = stu->getNext();
			}
			break;
		case'c':
			while (stu){
				if (stu->stu_score > 70 && stu->stu_score <= 80){
					stu->getMesg();
					++n;
				}
				stu = stu->getNext();
			}
			break;
		case'd':
			while (stu){
				if (stu->stu_score > 80 && stu->stu_score <= 90){
					stu->getMesg();
					++n;
				}
				stu = stu->getNext();
			}
			break;
		case'e':
			while (stu){
				if (stu->stu_score > 90 && stu->stu_score <= 100){
					stu->getMesg();
					++n;
				}
				stu = stu->getNext();
			}
			break;
		}
		if (n == 0){
			cout << "沒有改分數段的學生" << endl;
		}
	}
}

//對學生成績排序（2018.11.15更新)
void insertSort(Student* stu){
	Student* list = NULL;
	if (stu == NULL)
		return;
	else{
		list = (Student*)malloc(sizeof(Student));
		strcpy(list->stu_name, "");
		strcpy(list->stu_num, "");
		list->stu_score = 0;
		list->setNext(stu);
	}
	//保證有2個數據才排序
	if (list->getNext() == NULL || (list->getNext()->getNext() == NULL))
		return;
	Student *head, *p1, *p2, *prep1, *prep2, *temp;
	head = list;
	prep1 = head->getNext();
	p1 = prep1->getNext();

	bool flag;
	while (p1 != NULL){
		flag = true;
		temp = p1;
		for (prep2 = head, p2 = prep2->getNext(); p2 != p1; prep2 = prep2->getNext(), p2 = p2->getNext()){
			//從小打到排序
			if (p2->stu_score > p1->stu_score){
				//將p1節點拿出來
				p1 = p1->getNext();
				prep1->setNext(p1) ;
				//p1節點插入到p2之前
				prep2->setNext(temp);
				temp->setNext(p2);
				flag = false;//一個數據插入完成
				break;
			}
		}
		if (flag){			//處理後續數據
			prep1 = prep1->getNext();
			p1 = p1->getNext();
		}
	}
}




//主菜單
void menu(Student* stu){
	char selet[10];
	int n = 1;
	ofstream outfile;
	//ifstream infile;
	Student *p, *ptr,*mid;

	cout << "*************************歡迎進入學生信息管理系統*************************" << endl;
	do {
		cout << "**************************************************************************" << endl;
		cout << "1.插入信息；   2.刪除信息；  3.修改信息； 4.查看信息； 5.保存  " << endl;
		cout << "按'q'鍵退出      " << endl;
		cout << "**************************************************************************" << endl;

		cin >> selet;
		if (((selet[0]<'1' || selet[0]>'6') && selet[0] != 'q') || strlen(selet) > 1){
			//system("cls");
			cout << "您的輸入有誤，請重新輸入！" << endl;
			break;

		}
		switch (selet[0]){
		case'1':
			creatList(stu);
			break;
		case'2':
			delList(stu);
			break;
		case'3':
			changeInfo(stu);
			break;
		case'4':
			putStu(stu);
			break;
		case'5':
			outfile.open("student.txt", ios::out || ios::app);
			for (p = stu->getNext(); p != NULL; p = p->getNext()){
				outfile << p->stu_num << " ";
				outfile << p->stu_name << " ";
				outfile << p->stu_score << " ";
				outfile << endl;
			}
			outfile.close();
			system("cls");
			cout << "保存成功!" << endl;
			break;
		case'q':
			break;
		}

	} while (selet[0] != 'q');
}
int main(){
	Student head;
	menu(&head);
	system("pause");
}