example_files_student

#include "iostream"
#include "iomanip"
#include "fstream"
#include "string"
#include "ctype.h"
#include "conio.h"

using namespace std;
const unsigned MAX=3;

char *filename = "student.dat";  //��� �� �����
struct student //��������� �� �������
{
    string facNo; //���. �
    string Name;  //��� �� ��������
    double mark[MAX]; //������ �� ��� ��������
};

//������� �� ����������� ����� �� 1 �������
student set_value(string aFacNo, string aName, double m0, double m1, double m2)
{
    student stud;
    stud.facNo = aFacNo;
    stud.Name = aName;
    stud.mark[0] = m0;
    stud.mark[1] = m1;
    stud.mark[2] = m2;
    return stud;
}

//���� �� ��������� �������
char Display_menu()
{cout<<"\n\tMenu\nC - Create file\nW - Write to file\nR - Read from file"
    <<"\nA - Append a redor\nU - Updete a redord\nD - Delete a record"
    <<"\nF - Find data\nE - Exit program\n    Youre choice: ";
 char choice;
 choice = _getch();
 choice =toupper(choice);
 return choice;
}

//������� �� ��������� �� ������� �� 1 �������
void Input(student &stud)
{
    cout<<"\nfacNo: "; getline(cin,stud.facNo,'\n');
    cout<<"name: "; getline(cin,stud.Name,'\n');
    for(int i = 0; i<MAX; i++)
        {
            cout<<"mark["<<i+1<<"] = ";
            cin>>stud.mark[i];
        }
}

//������� �� ����������� ������� �� 1 �������
void Output(student stud)
{
    cout<<setw(10)<<setiosflags(ios::left)<<stud.facNo
        <<setw(25)<<setiosflags(ios::left)<<stud.Name;
    cout<<resetiosflags(ios::left);
    for(int i=0; i<MAX; i++)
        cout<<setw(6)<<setprecision(2)<<setiosflags(ios::fixed)
            <<stud.mark[i];
    cout<<endl;
}

//������� �� ��������� �� ������ ����
void Create_file(char *fname)
{
    fstream students;
    student stud;
    students.open(fname,ios::in);
    if(!students) //������ �� ���� �� ���� �������
        {
            cerr<<"File couldn't be opened\n";
            cout<<"Create a new file...\n";
            students.open(fname,ios::out); //������ ��� ����
            students.close();
            return;
        }
    students.seekg(0,ios::end); //���������� get ��������� � ���� �� �����
    streamoff size_file;
    size_file = students.tellg(); //�������� ������� �� �����
    cout<<"file isn't empty. It has "
        <<size_file/sizeof(student)<<" records.\n";
    char Answer;
    cout<<"Delete file? (Y/N): ";
        Answer = _getch();Answer = toupper(Answer);
    if(Answer != 'Y')
            {
                students.close();
                return;
            }
    students.clear();
    students.seekg(0);
    students.close();
    students.open(fname,ios::out|ios::trunc);
    students.close();

}
//������� �� ��������� �� ����, ���� �������� ������ ������������ � ����.
void Write_to_file(char *fname)
{
    ofstream students;
    student stud;
    students.open(fname,ios::out);
    long i, count;
    cout<<"Enter count of students = ";
    cin>>count;
    for(i=0;i<count; i++)
        {
            cin.ignore();
            Input(stud);
            students.write(reinterpret_cast<char *> (&stud),sizeof(student));
        }
    students.close();
}

//������� �� ������ �� ������� �� ���� � ��������� �� �� ������
void Read_from_file(char *filename)
{
    ifstream students;
    student s;
    students.open(filename, ios::in);
    students.clear();
    students.seekg(0);
    while(students.read(reinterpret_cast<char*>(&s),sizeof(student)))
        {
            Output(s);
            if(students.eof()) break;
        }
    students.close();
}

//������� ���������� �� ����� � ���� �� �����
void Append_to_file(char *filename)
{
    ofstream students;
    student stud;
    int i,count;
    students.open (filename,ios::app);
    students.seekp(0,ios::end);
    cout<<"Enter count of students = ";
    cin>>count;
    for(i=0;i<count; i++)
        {
            cin.ignore();
            Input(stud);
            students.write(reinterpret_cast<char *> (&stud),sizeof(student));
        }
    students.close();
}

//������� �� ���������� �� ���� ����� ��� �����
void Update_record(char *filename)
{
    fstream students;
    student stud;
    students.open(filename, ios::in);
    students.clear();
    students.seekg(0);
    streamoff record;
    cout<<"Enter record "; cin>>record;
    students.seekg((record-1)*sizeof(student));
    students.read(reinterpret_cast<char*>(&stud),sizeof(student));
    Output(stud);
    char Answer;
    cout<<"Update record? (Y/N): ";
        Answer = _getch();Answer = toupper(Answer);
    if(Answer != 'Y')
            {
                students.close();
                return;
            }
    students.close();
    cin.ignore();
    Input(stud);
    students.open(filename, ios::ate| ios::out |ios::_Nocreate);
    students.clear();
    students.seekp((record-1)*sizeof(student));
    students.write(reinterpret_cast<char *> (&stud),sizeof(student));
    students.seekp(0,ios::end);
    students.close();
}

//������� �� ��������� �� ���� ����� ��� ����� - �������� ������ � ������ �����
void Dlete_record(char *filename)
{
    fstream students;
    student stud;
    students.open(filename, ios::in);
    students.clear();
    students.seekg(0);
    streamoff record;
    cout<<"Enter record "; cin>>record;
    students.seekg((record-1)*sizeof(student));
    students.read(reinterpret_cast<char*>(&stud),sizeof(student));
    Output(stud);
    char Answer;
    cout<<"Delete record? (Y/N): ";
        Answer = _getch();Answer = toupper(Answer);
    if(Answer != 'Y')
            {
                students.close();
                return;
            }
    students.close();
    cin.ignore();
    stud =set_value("no FacNo","No Name",0,0,0);
    students.open(filename, ios::ate| ios::out |ios::_Nocreate);
    students.clear();
    students.seekp((record-1)*sizeof(student));
    students.write(reinterpret_cast<char *> (&stud),sizeof(student));
    students.seekp(0,ios::end);
    students.close();


}

//������� �� ���������� ������� ����� �� 1 �������
double results(student stud)
{
    double result =0;
    for(int i=0; i<MAX; i++)
        result+=stud.mark[0];
    return result/MAX;
}

//������� �� ��������� �� ���������� �� ��������� �������
//  ������� �� ����� ������� �� ������� ���.�
// ������� ����� �� ������ ��������
// ��������� ��� �������� ����
void Find_data(char *filename)
{
    ifstream students;
    student s;
    students.open(filename, ios::in);


    char ch;
    do
    {
        cout<<"\nI - Information for student\nR - Results for students\n"
            <<"E - End find\nYour choice: ";
        ch = _getch();
        ch=toupper(ch);
        switch(ch)
        {
        case 'I':{cout<<"\nInformation for student\n";//���������� �� 1 �������
                  string aFacNo;
                  cout<<"Enter FacNo: ";
                  getline(cin,aFacNo);
                  students.clear();
                  students.seekg(0);
                   while(students.read(reinterpret_cast<char*>(&s),sizeof(student)))
                    {
                        if(aFacNo.compare(s.facNo)==0) Output(s);
                        if(students.eof()) break;
                    }
                  break;}
        case 'R':{cout<<"\nR-Results for students\n";
                  students.clear();
                  students.seekg(0);
                  while(students.read(reinterpret_cast<char*>(&s),sizeof(student)))
                    {
                        cout<<setw(10)<<setiosflags(ios::left)<<s.facNo
                            <<setw(30)<<setiosflags(ios::left)<<s.Name
                            <<setw(10)<<setprecision(2)
                            <<setiosflags(ios::fixed)<<results(s)<<endl;
                        if(students.eof()) break;
                    }
                  break;}
        case 'E':{cout<<"\nEnd search...\n";break;}
        default:{cout<<"\nIncald choice...\n";break;}
        }
    } while(ch !='E');
    students.close();
}
int main()
{
    char choice;
    do
    {
        choice = Display_menu();
        switch(choice)
        {
            case 'C': {
                        cout<<"\nCreate empty file\n";
                        Create_file(filename);
                        break;
                      }
            case 'W':{
                        cout<<"\nWrite to file\n";
                        Write_to_file(filename);
                        break;
                      }
            case 'R': {
                        cout<<"\nRead_from_file\n";
                        Read_from_file(filename);
                        break;
                       }
            case 'A': {
                        cout<<"\nAppend a record\n";
                        Append_to_file(filename);
                        break;
                       }
            case 'U': {
                        cout<<"\nUpdete a redord\n";
                        Update_record(filename);
                        break;
                       }
            case 'D': {
                        cout<<"\nDelete a redord\n";
                        Dlete_record(filename);
                        break;
                       }
            case 'F': {cout<<"\nFind data\n";
                        Find_data(filename);
                        break;
                       }
            case 'E' :{cout<<"\nExit program...\n"; break;}
            default:{cout<<"Invalid choice...\n"; break;}
        }

    }
    while(choice != 'E');
    cout<<"\nPress any key....";
    _getch();
    return 0;
}