C++学生信息管理系统

平台：Window，Linux都可

语言：C++

完成日期：2017.1.17

功能：能打开程序时，自动加载已经在文件中的数据，那文件就相当于数据库，当关闭程序时，自动保存数据到文件中。

          当然增加，删除，修改，排序，清空等也是必不可少的。但这个学生信息有点少，我就写了名字和号码。其他成绩什么的就不加进去了，尽量显得简单。

#include<iostream>#include<fstream> #include<string.h> using namespace std;/*学生信息结点*/class Student{public:char name[20];int num;Student *next;void input();void ReadFile(ifstream &in);};/*往结点输入信息*/void Student::input(){cout<<"please enter student's name:";cin>>name;cout<<"please enter student's num:";cin>>num;return ; }/*从文档中读取值到结点*/void Student::ReadFile(ifstream &in){in>>name>>num;}/*学生信息结点链表*/class StudentMessage{public:StudentMessage();~StudentMessage();/*关于学生信息这个类所用到的函数*/void Show_Menu();void Add_Node();void Del_node();void Display();void Find(); void Modify();void Load();void Save();void Clean();void Swap_node(Student *q,Student*p);void Sort(); private: /*StudentMessage类可以看作是以Studet类为结点的链表*/ Student *head;  //链表头 Student *end;//链表尾 ifstream in;ofstream out;};/*构造函数*//*这个构造函数可以在打开程序时，就自动加载原有的学生信息*/ StudentMessage::StudentMessage(){/*初始化，头尾结点*/ head = new Student;head->next = new Student;end = head->next; ifstream in("file.txt"); //原有的学生信息是放在文件file.txt中的 /*Important Part！*//*下面很关键，不这样做的话达不到效果。首先要先向文件读一下，才能判断文件是否为空，因为eof()不能用来判断文件是否为空，eof()是根据文件的状态标识来判断文件是否为空的，当读取文件时，遇到结尾时，系统会改变文件的状态标识，这时候才会返回EOF，才能用eof()判断。不先读一下的话，in.eof()是不会返回正值的，即使文件为空*/char ch = in.get();if(in.eof()){cout<<"file is empty"<<endl;}/*若文件非空*/while(!in.eof()){end->ReadFile(in);if(end->name[0]=='\0')break;  //这里也是比较关键的，不加这一句的话 //程序会把文件最后结束的标记也都出来end->next = new Student;end = end->next;}}/*析构函数*/StudentMessage::~StudentMessage(){Save();    //当正常退出程序的时候，保存数据到file.txt中 Student *pos = head->next;Student *temp;while(pos!=end){temp = pos;pos = pos->next;delete temp;}delete head,end;}/*/*增加结点*/void StudentMessage::Add_Node(){char quit;while(1){end->input();end->next = new Student;end = end->next;cout<<"continue or not?,Y/N"<<endl;cin>>quit;switch(quit){case'Y':case'y':break;case'n':case'N':return;break;default:cout<<"error input,again,please..Y/N";cin>>quit;}}cout<<"add node success!"<<endl;system("pause");}/*修改结点*/void StudentMessage::Modify(){char name[20];cout<<"enter the name you want to modify:";cin>>name;Student *pos = head->next;for(pos;pos!=end;pos=pos->next){if(strcmp(name,pos->name)==0){pos->input();break;}}cout<<"Modify success!..."<<endl;system("pause");} /*删除结点*/void StudentMessage::Del_node(){int del_flag = 0;char name[20];if(head->next == end){cout<<"Empty...."<<endl;return;}cout<<"please enter the name you want to delete:";cin>>name;Student *p = head->next;Student *q = head; for(p;p!=end;p->next){if(strcmp(p->name,name)==0) {del_flag = 1;q->next = p->next;delete p;break;}else{q=q->next;p=p->next;}}if(del_flag == 0){cout<<"Can not Find the name you want."<<endl;}cout<<"del node success!"<<endl;system("pause");} /*查找学生信息*/void StudentMessage::Find(){char name[20];cout<<"please enter name you want to find:";cin>>name;Student *pos = head->next;if(pos==end){cout<<"Student Message is Empty..."<<endl;return ;}for(pos;pos!=end;pos=pos->next){if(strcmp(pos->name,name)==0){cout<<"Find it!"<<endl;cout<<"name:"<<pos->name<<endl;cout<<"num:"<<pos->num<<endl;return;}}cout<<"Can not Find the name...";}/*保存学生信息*/void StudentMessage::Save(){out.open("file.txt");Student *pos = head->next;if(head->next== end){cout<<"StudentMessage List is Empty...."<<endl;return ;}else{for(pos;pos!=end;pos=pos->next){out<<'\t'<<pos->name<<'\t'<<pos->num;//格式最好这样写//因为一开始会把文件读一下，以判断//文件是否为空，所以前面最后用‘\t’//来增加几个空格，给他读一个空格，//以不读到正常数据，后面就不要有空格//以为当程序从file.txt读信息时，可能//会把空格也当是一个数据结点读进程序}}out.close();cout<<"Save node success!"<<endl;}/*显示结点*/void StudentMessage::Display(){if(head->next==end){cout<<"Empty..."<<endl;}Student *pos;pos = head->next;for(pos;pos!=end;pos=pos->next){cout<<endl;cout<<pos->name<<endl;cout<<pos->num<<endl;cout<<endl;}system("pause");}/*结点交换*/void StudentMessage::Swap_node(Student *q,Student *p){char Tname[20];int Tnum;strcpy(Tname,p->name);Tnum = p->num;strcpy(p->name,q->name);p->num = q->num;strcpy(q->name,Tname);q->num = Tnum;}/*以num位准排序*/void StudentMessage::Sort(){Student *p,*q;p=head->next;/*冒泡排序*/for(p;p!=end;p=p->next){for(q=p->next;q!=end;q=q->next){if(q->num > p->num){Swap_node(q,p);}}} cout<<"sort success!"<<endl;system("pause");}/*清空文档*/void StudentMessage::Clean(){ofstream out("file.txt",ios::trunc);out.close();exit(0);//用exit使程序退出程序的时候，不调用StudentMessage类的析构函数，//否则又会把内存的数据写到file.txt文件中 }/*显示菜单*/void StudentMessage::Show_Menu(){cout<<"0.退出程序"<<endl;cout<<"1.增加结点"<<endl;cout<<"2.删除结点"<<endl;cout<<"3.显示所有学生信息"<<endl; cout<<"4.修改学生信息"<<endl; cout<<"5.查找学生信息"<<endl;cout<<"6.清空文档"<<endl;cout<<"7.排序"<<endl; } int main(){StudentMessage sm;    //创建类对象，并调用其构造函数     //把file.txt中的学生信息数据读到内存中int choice;while(1){sm.Show_Menu();cout<<"please enter your choice:";cin>>choice;switch(choice){case 0:return 0;break;case 1:sm.Add_Node();break;case 2:sm.Del_node();break;case 3:sm.Display();break;case 4:sm.Modify();break;case 5:sm.Find();break;case 6:sm.Clean();break;case 7:sm.Sort();break;}system("cls");}return 0;}