project12.cpp

/* Name: Keita Nonaka
 Project 12

 This program is for using files.
 There are 5 commands to handle person data
 */

#include <iostream>
#include <iomanip>
#include <fstream>
#include "Person.h"

using namespace std;

char enterChoice();
void createTextFile(fstream&);
void updateRecord(fstream&);
void newRecord(fstream&);
void deleteRecord(fstream&);
void outputLine(ostream&, const Person &);
int getidNumber(const char * const);


int main() {
    char ans;
    cout<<"Do you want to create an empty file (y/n)? ";
    cin >> ans;
    if (ans=='y' || ans=='Y'){
            //create nameage.dat to hold 100 possible person objects
        ofstream outPerson("nameage.dat", ios::out | ios::binary);
        
            // exit program if ofstream could not open file
        if (!outPerson){
            cerr << "File could not be opened." << endl;
            exit(1);
        }
        
        Person blankPerson; // constructor zeros out each data member
        
            // output 100 blank records to file
        for (int i = 0; i < 100; ++i) {
            outPerson.write(reinterpret_cast< const char * >(&blankPerson), sizeof(Person));
        }
        outPerson.close();
    }
    
    fstream inOutPerson("nameage.dat", ios::in | ios::out | ios::binary);
    char choice = '\0';
    
    while ((choice = enterChoice()) != 'E' && choice != 'e') {
        switch (choice) {
            case 'P':
            case 'p':// print/display data
                createTextFile(inOutPerson);
                break;
            case 'U':
            case 'u':// update record
                updateRecord(inOutPerson);
                break;
            case 'A':
            case 'a':// add a new record
                newRecord(inOutPerson);
                break;
            case 'D':
            case 'd':// delete existing record
                deleteRecord(inOutPerson);
                break;
            default: // display error if user does not select valid choice
                cerr << "Incorrect choice" << endl;
                break;
        }
        inOutPerson.clear(); // reset
    }
}

// enable user to input menu choice
char enterChoice() {
    // display available options
    cout << "\nEnter your choice" << endl
         << "P - Print/Display a list of people" << endl
         << "U - Update a person" << endl
         << "A - Add a new person" << endl
         << "D - Delete a person" << endl
         << "E - End program\n> ";
    
    char menuChoice;
    cin >> menuChoice; // input menu selection from user
    return menuChoice;
}

// create formatted text file for printing (uses nameage.dat as input)
void createTextFile(fstream &readFromFile) {
    // create text file
    ofstream outPrintFile("print.txt", ios::out);
    // exit program if ofstream cannot create file
    if (!outPrintFile) {
        cout << "File could not be created." << endl;
        exit(1);
    }
    //display header information to file and to cout
    cout << left << setw( 10 ) << "id" << setw( 16 ) << "Last name" << setw( 11 ) << "first name" << setw( 10 ) << right  << "age" << endl;
    outPrintFile << left << setw( 10 ) << "id" << setw( 16 ) << "Last name" << setw( 11 ) << "first name" << setw( 10 ) << right  << "age" << endl;

    // set file-position pointer to beginning of readFromFile
    readFromFile.seekg(0);
    // read first record from record file
    Person person;
    readFromFile.read(reinterpret_cast<char *>(&person), sizeof(Person));

    // copy all records from record file into text file
    while (!readFromFile.eof()) { // write single record to text file
        if (person.getId() != 0) {
            outputLine(cout,person);
            outputLine(outPrintFile,person);
        }
        
        // read next record from record file
        readFromFile.read(reinterpret_cast<char *>(&person), sizeof(Person));
    }
}

// update age in record
void updateRecord( fstream &updateFile ) {
    // obtain number of idNumber to update
    int idNumber = getidNumber("Enter Id Number to update");
    Person person;
    
    // move file-position pointer to correct record in file
    updateFile.seekg((idNumber - 1) * sizeof(Person));
    
    // read first record from file
    updateFile.read(reinterpret_cast<char *>(&person), sizeof(Person));
    //update record
    if(person.getId() != 0) {
        outputLine(cout, person); // display the record
        
        // request user to update age
        cout << "\nEnter new age:" << endl;
        int age; 
        cin >> age;
        
        // update age
        person.setAge(age);
        // move file-position pointer to correct record in file
        updateFile.seekp((idNumber - 1) * sizeof(Person));
        // write updated record over old record in file
        updateFile.write(reinterpret_cast<const char *>(&person), sizeof(Person));
    } else{ // display error if idNumber does not exist
        cerr << "Id # " << idNumber << " has no information." << endl;
    }
}

// create and insert record
void newRecord(fstream &insertInFile) {
    // obtain number of idNumber to create
    int idNumber = getidNumber("Enter new Id Number");
    Person person;
    
    // move file-position pointer to correct record in file
    insertInFile.seekg((idNumber-1) * sizeof(Person));
    // read record from file
    insertInFile.read(reinterpret_cast<char *>(&person), sizeof(Person));

    // create record, if record does not previously exist
    if (person.getId() == 0) {
        string lastName;
        string firstName;
        int age;
        
        // user enters last name, first name and age
        cout << "Enter lastname, firstname, age\n> ";
        cin >> setw( 15 ) >> lastName;
        cin >> setw( 10 ) >> firstName;
        cin >> age;

        person.setId(idNumber);
        person.setFirstName(firstName);
        person.setLastName(lastName);
        person.setAge(age);

        // insert record in file
        insertInFile.seekp((idNumber-1) * sizeof(Person));
        insertInFile.write(reinterpret_cast<const char *>(&person), sizeof(Person));
    } else { // display error if idNumber already exists
        cerr << "Id # " << idNumber << " already contains information." << endl;
    }
}

// delete an existing record
void deleteRecord( fstream &deleteFromFile ) {
    // obtain number of idNumber to delete
    int idNumber = getidNumber("Enter Id Number to delete");
    Person person;
    
    // move file-position pointer to correct record in file
    deleteFromFile.seekg((idNumber-1) * sizeof(Person));
    // read record from file
    deleteFromFile.read(reinterpret_cast<char *>(&person), sizeof(Person));
    // delete record, if record exists in file
    if(person.getId() != 0) {
        Person blankPerson; // create blank record
        
        // move file-position pointer to correct record in file
        deleteFromFile.seekp((idNumber-1) * sizeof(Person));
        // replace existing record with blank record
        deleteFromFile.write(reinterpret_cast<char *>(&blankPerson), sizeof(Person));
        
        cout << "Id #" << idNumber << " deleted.\n";
    } else{ // display error if idNumber does not exist
        cerr << "Id #" << idNumber << " is empty" << endl;
    }
}

// display single record
void outputLine( ostream &output, const Person &record ) {
    output << left << setw( 10 ) << record.getId() << setw( 16 ) << record.getLastName()
           << setw( 11 ) << record.getFirstName() << setw( 10 ) << right << record.getAge() << endl;
}

// obtain idNumber-number value from user
int getidNumber(const char * const prompt) {
    int idNumber;

    do {
        cout << prompt << " (1-100): ";
        cin >> idNumber;
    } while (idNumber < 1 || idNumber > 100);
    
    return idNumber;
}