【生生被气死的一周】头秃

//**************************************************************************************************************
//作者：
//日期：2018/3/19
//学号：
//题号：5-5
//题目：编写一个程序，实现以下功能：

//      1)输入一系列的学生数据（包括学生的学号、姓名和成绩等基本信息），将学生信息写入二进制文件student.dat中。

//      2)从student.dat文件中读出这些数据并显示出来。

//      3)在student.dat文件中按姓名进行查询，如输入“李”，则将所有姓“李”的学生的   数据显示出来。

//      4)可对指定学生的数据进行修改。

//      5)可以删除指定的学生数据。

//**************************************************************************************************************



#include<iostream>
#include<fstream>
#include<stdlib.h>
#include<cstring>
using namespace std;
struct Std
{
    char name[20];
    char id[20];
    char score[5];
};
void getinfo(char filename[]);
void showinfo(char filename[]);
void searchinfo(char filename[]);
void editinfo(char filename[]);
void deleteinfo(char filename[]);

int main()
{
    fstream student;
    char choice;
    char filename[20];
    cout << "Please type in the filename:";
    cin.getline(filename,20);
    cout << endl;
    while(true)
    {
        cout << "Please type down the manipulation code:\nA.Input information\tB.Show information\tC.Search\tD.Edit\tE.Delete\tF.Exit\n";
        cout << endl;
        cin >> choice;
        switch(choice)
        {
            case'A':
            case'a':getinfo(filename);break;
            case'B':
            case'b':showinfo(filename);break;
            case'C':
            case'c':searchinfo(filename);break;
            case'D':
            case'd':editinfo(filename);break;
            case'E':
            case'e':deleteinfo(filename);break;
            case'F':
            case'f':exit(0);
        }
        cout << endl;
    }
    return 0;
}

void getinfo(char filename[])
{
    fstream student;
    student.open(filename,ios::out|ios::binary);
    if(!student)
    {
        cout << "Error!";
        exit(0);
    }
    int count;
    cout << "How many student's information would you like to input?";
    cin >> count;
    Std *Student;
    Student = new struct Std[count];
    for(int i=0;i<count;i++)
    {
        cout << "Please input student "<<i+1<<" 's name:";
        cin.get();
        cin.getline(Student[i].name,20);
        cout << "Please input student "<<i+1<<" 's id:";
        cin.getline(Student[i].id,20);
        cout << "Please input student "<<i+1<<" 's score:";
        cin >> Student[i].score;
        student.write((char*)&Student[i],sizeof(Student[i]));
    }
    cout << "Done.";
    delete[]Student;
    student.close();
}

void showinfo(char filename[])
{
    fstream student;
    student.open(filename,ios::in|ios::binary);
    if(!student)
    {
        cout << "Error!";
        exit(0);
    }
    Std Student;
    student.read((char*)&Student,sizeof(Student));
    while(!student.eof())
    {
        cout << "name:";
        cout << Student.name <<endl;
        cout << "id:";
        cout << Student.id <<endl;
        cout << "score:";
        cout << Student.score <<endl;
        student.read((char*)&Student,sizeof(Student));
    }
    cout << "Above are all the information."<<endl;
    student.close();
}

void searchinfo(char filename[])
{
    fstream student;
    Std Student;
    student.open(filename,ios::in|ios::binary);
    if(!student)
    {
        cout << "Error!";
        exit(0);
    }
    char ch,Name;
    cout << "Please input the first name:";
    cin >> Name;
    long position = student.tellg();
    cout << "position:"<<position<<endl;
    student.seekg(0L,ios::beg);
    student.get(ch);
    cout << "ch:"<<ch<<endl;
    //cout << "\nch:"<<ch<<endl;
    position = student.tellg();
    cout << "position:"<<position<<endl;
    student.seekg(0L,ios::beg);
    long current_pos = 0L;
    while(!student.eof())
    {
        if(ch == Name)
        {
            cout << "ch:"<<ch<<endl;
            student.read((char*)&Student,sizeof(Student));
            long position;
            position = student.tellg();
            cout << "position:"<<position<<endl;
            cout << "name:";
            cout << Student.name <<endl;
            cout << "id:";
            cout << Student.id <<endl;
            cout << "score:";
            cout << Student.score <<endl;
            student.seekg(-(sizeof(Student)),ios::cur);
            position = student.tellg();
            cout << "position:"<<position<<endl;
        }
        current_pos = current_pos + sizeof(Student);
        student.seekg(current_pos,ios::cur);
  //      long position = student.tellg();
 //           cout << "position:"<<position<<endl;
        //student.seekg(1L,ios::cur);
        //cin.ignore();
        //position = student.tellg();
        //cout << "position:"<<position<<endl;
 //       student.get(ch);
 //       position = student.tellg();
 //           cout << "position:"<<position<<endl;
  //      student.seekg(-sizeof(ch),ios::cur);
   //     position = student.tellg();
//s            cout << "position:"<<position<<endl;
    }
    cout << "Above are all the information that you are looking for."<<endl;
    student.close();
}

void editinfo(char filename[])
{
    fstream student;
    Std Student;
    student.open(filename,ios::in|ios::out|ios::binary);
    if(!student)
    {
        cout << "Error!";
        exit(0);
    }
    char editid[20];
    cout << "Please input the id of the student whose information needs to be edited:";
    cin >> editid;
    student.seekg(0L,ios::beg);
    student.seekg(sizeof(Student.name),ios::beg);
    student.seekp(0L,ios::beg);
    student.read((char*)&Student.id,sizeof(Student.id));
    while(!student.eof())
    {
        if(strcmp(editid,Student.id)==0)
        {
            student.seekg(-sizeof(Student.id)-sizeof(Student.name),ios::cur);
            student.read((char*)&Student,sizeof(Student));
            cout << "The information of the student:"<<endl;
            cout << "name:"<<Student.name<<endl;
            cout << "id:"<<Student.id<<endl;
            cout << "score:"<<Student.score<<endl;
            cout << "Now please input the new information:";
            cout << "name:";
            cin >> Student.name;
            cout << "id:";
            cin >> Student.id;
            cout << "score:";
            cin >> Student.score;
            student.write((char*)&Student,sizeof(Student));
            break;
        }
        student.seekg(sizeof(Student),ios::cur);
        student.seekp(sizeof(Student),ios::cur);
    }
    cout << "Done.";
    student.close();
}

void deleteinfo(char filename[])
{
    fstream student;
    Std Student;
    student.open(filename,ios::in|ios::out|ios::binary);
    if(!student)
    {
        cout << "Error!";
        exit(0);
    }
    char deleid[20];
    cout << "Please input the id of the student whose information needs to be erased:";
    cin >> deleid;
    student.seekg(0L,ios::beg);
    student.seekg(sizeof(Student.name),ios::beg);
    student.seekp(0L,ios::beg);
    student.read((char*)&Student.id,sizeof(Student.id));
    while(!student.eof())
    {
        if(strcmp(deleid,Student.id)==0)
        {
            student.seekg(-sizeof(Student.id)-sizeof(Student.name),ios::cur);
            student.read((char*)&Student,sizeof(Student));
            cout << "The information of the student:"<<endl;
            cout << "name:"<<Student.name<<endl;
            cout << "id:"<<Student.id<<endl;
            cout << "score:"<<Student.score<<endl;
            cout << "type 'd' to delete this student's information:";
            char code;
            cin >> code;
            if(code == 'd')
            {
                strcpy(Student.name,0);
                strcpy(Student.id,0);
                strcpy(Student.score,0);
            }
            student.write((char*)&Student,sizeof(Student));
            break;
        }
        student.seekg(sizeof(Student),ios::cur);
        student.seekp(sizeof(Student),ios::cur);
    }
    cout << "Done.";
    student.close();
}