Как я могу найти и отобразить что-то в файле данных?

Question

#include <fstream>
#include <iomanip>
#include <iostream>
#include <conio.h>
#include <math.h>
#include <stdlib.h>

using namespace std;

int main() {
    int option, recordnum, count = 0;
    float grosspay, hours, payrate, taxes, taxrate, netpay, taxp, payamount;
    char firstname[10], lastname[10], employid[10], again = 'y';

    do {
        system("cls");
        cout << "Enter An Option.\n";
        cout << "1. Write new Records to the Data File.\n";
        cout << "2. Display Records from the Data File.\n";
        cout << "3. Find all records with a pay rate less than $ N dollar per "
                "hour.\n";
        cout << "4. Exit\n";
        cout << "What would you like to do?: ";
        cin >> option;
        option = fabs(option);

        if(option < 1 or option > 4) {
            system("cls");
            cout << "Enter An Option.\n";
            cout << "1. Write new Records to the Data File.\n";
            cout << "2. Display Records from the Data File.\n";
            cout << "3. Find all records with a pay rate less than $ N dollar per "
                    "hour.\n";
            cout << "4. Exit\n";
            cout << "What would you like to do?: "
                 << "\n";
            cin >> option;
        }

        system("cls");
        switch(option) {
        case 1: {
            ofstream outFile("personnel.dat", ios::out | ios::app);
            outFile.precision(2);
            outFile.setf(ios::fixed);

            cout << "How Many Records Do You Want to Enter?: ";
            cin >> recordnum;
            recordnum = abs(recordnum);

            if(recordnum == 0) break;

            for(int count = 1; count <= recordnum; count++) {
                system("cls");
                cout << "Enter Employee's First Name: ";
                cin >> firstname;
                cout << "Enter Employee's Last Name: ";
                cin >> lastname;
                cout << "Enter Employee's ID #: ";
                cin >> employid;
                cout << "Enter Employee's Hours Worked: ";
                cin >> hours;
                hours = fabs(hours);
                cout << "Enter Employee's Pay Rate: ";
                cin >> payrate;
                payrate = fabs(payrate);
                cout << "Enter Employee's Tax Rate: ";
                cin >> taxrate;
                taxrate = fabs(taxrate);

                grosspay = hours * payrate;
                taxes = grosspay * taxrate;
                netpay = grosspay * taxes;

                outFile << firstname << " " << lastname << " " << employid << " "
                        << hours << " " << payrate << " " << taxrate << " "
                        << grosspay << " " << taxes << " " << netpay << " "
                        << "\n";
            }
            outFile.close();
            break;
        }
        case 2: {
            ifstream inFile("personnel.dat", ios::in);
            inFile >> firstname >> lastname >> employid >> hours >> payrate >>
                taxrate >> grosspay >> taxes >> netpay;

            while(!inFile.eof()) {
                count++;
                taxp = taxrate * 100;
                cout << "\n\n Record Number: " << count;
                cout << "\n\n First Name: " << firstname;
                cout << "\n\n Last Name: " << lastname;
                cout << "\n\n Employee's ID #: " << employid;
                cout << "\n\n Hours Worked: " << hours;
                cout << "\n\n Pay Rate: " << payrate;
                cout << "\n\n Gross Pay: $" << grosspay;
                cout << "\n\n Taxes: " << taxes;
                cout << "\n\n Net Pay: $" << netpay;
                cout << "\n\n Tax Rate: " << taxp << "%";
                inFile >> firstname >> lastname >> employid >> hours >> payrate >>
                    taxrate >> grosspay >> taxes >> netpay;
            }

            cout << "\n\n Total Numbers of Files: " << count;
            inFile.close();
            count = 0;
            cout << "\n\n Press Any Keys to Continue...";
            getch();
            break;
        }
        case 3: {
            cout << "Enter the Pay Rate amount to Find All Employee's Pay Rate Less "
                    "than: ";
            cin >> payamount;

            for(payamount = payamount; payamount <= payamount; payamount++) {
            }
        }
        }
        while(again == 'y')
            ;
    }
}

Итак, для случая 3 я должен найти сумму оплаты, которая меньше введенной суммы, и отобразить ее. Но мне также нужно отобразить все вместе с этой суммой оплаты, то есть имя, фамилию, empid и т. Д. Нужно ли мне делать еще один inFile вместе с циклом for? или я должен был бы сделать что-то еще?

Answer 1

В случае 3 требуется выполнить фильтрацию данных. Вы должны проверить состояние фильтра перед печатью данных. Очень грубый способ сделать это следующим образом:

/* ... */

cin >> payamount;

ifstream inFile("personnel.dat", ios::in);

while((inFile >> firstname >> lastname >> employid >> hours >> payrate >>
                taxrate >> grosspay >> taxes >> netpay)) {
    if(netpay < payamount) // this might not be correct, change it to your own criteria if it's wrong
    {

        count++;
        taxp = taxrate * 100;
        cout << "\n\n Record Number: " << count;
        cout << "\n\n First Name: " << firstname;
        cout << "\n\n Last Name: " << lastname;
        cout << "\n\n Employee's ID #: " << employid;
        cout << "\n\n Hours Worked: " << hours;
        cout << "\n\n Pay Rate: " << payrate;
        cout << "\n\n Gross Pay: $" << grosspay;
        cout << "\n\n Taxes: " << taxes;
        cout << "\n\n Net Pay: $" << netpay;
        cout << "\n\n Tax Rate: " << taxp << "%";
    }
}

cout << "\n\n Total Numbers of Files: " << count;
inFile.close();
count = 0;
cout << "\n\n Press Any Keys to Continue...";
getch();
break;
/* ... */

... но я настоятельно рекомендую определить структуру / класс для сотрудника и сделать блок кода печати сотрудника функцией. Также я заменил (! InFile.eof ()) на потоковое выражение, предложенное другими участниками для обсуждения этого вопроса.