Why Can't Read The File(doesn't display the data)?

Question

*i Want to get from the user his address and store it in file.dat then display these data
For Example:

                    First Name: joooooosh
                    Last Name: Mikeeeeee
                    Governorate: Gize
                    City: 6 October132
                    Area: 4th District
                    Street Name/NO. : Conrad, 42, Washington, D.C.
                    Mobile: 123456789
                    Building Name/No. : 833
                    Floor No. : 3
                    Apartment No. : 7
                    Nearest Landmark: Pharmacy*

and when read from file to display, doesn't show any thing, Why?
this code is part from my project, This is my complete project https://github.com/loai1929/Bookshop-Management-System.git
Thanks in advance.

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <fstream>
#include <string.h>
#include <conio.h>
using namespace std;


class Adress
{
public:
    char area[50], first_name[20], last_name[20], governorate[30], city[20], street_name[100], mobile[15], building_name[20], floor_no[10], apartment_no[5], nearest_landmark[50];
    void dis_ad();
    void display_adress();
    void get_adress();
};

void Adress::get_adress()
{

    cout << "\n\n\t\t\tMy Address:-\n\n\t\t\tFirst Name: ";
    cin.getline(first_name, 20);
    cout << "\n\n\t\t\tLast Name: ";
    cin.getline(last_name, 20);
    cout << "\n\n\t\t\tGovernorate: ";
    cin.getline(governorate, 30);
    cout << "\n\n\t\t\tCity: ";
    cin.getline(city, 20);
    cout << "\n\n\t\t\tArea: ";
    cin.getline(area, 50);
    cout << "\n\n\t\t\tStreet Name/NO. : ";
    cin.getline(street_name, 100);
    cout << "\n\n\t\t\tMobile: ";
    cin.getline(mobile, 15);
    cout << "\n\n\n\t\t\tBuilding Name/No. : ";
    cin.getline(building_name, 20);
    cout << "\n\n\t\t\tFloor No. : ";
    cin.getline(floor_no, 10);
    cout << "\n\n\t\t\tApartment No. : ";
    cin.getline(apartment_no, 5);
    cout << "\n\n\t\t\tNearest Landmark: ";
    cin.getline(nearest_landmark, 50);
}
void Adress::display_adress()
{

    cout << "\n\n\t\t\tFirst Name: " << first_name;
    cout << "\n\n\t\t\tLast Name: " << last_name;
    cout << "\n\n\t\t\tGovernorate: " << governorate;
    cout << "\n\n\t\t\tCity: " << city;
    cout << "\n\n\t\t\tArea: " << area;
    cout << "\n\n\t\t\tStreet Name/NO. : " << street_name;
    cout << "\n\n\t\t\tMobile: " << mobile;
    cout << "\n\n\n\t\t\tBuilding Name/No. : " << building_name;
    cout << "\n\n\t\t\tFloor No. : " << floor_no;
    cout << "\n\n\t\t\tFloor No. : " << apartment_no;
    cout << "\n\n\t\t\tNearest Landmark: " << nearest_landmark;
}
void Adress::dis_ad()
{
    ifstream iFile("shippingAddresses.dat", ios::binary);
    while (iFile.read((char *)this, sizeof(*this)))
    {
        display_adress();
    }
    iFile.close();
}
int main()
{
    Adress ad;
    ad.dis_ad();
}

I'd guess opening of `iFile` fails causing `read` to fail meaning your while loop body never executes — Alan Birtles, Aug 07 '21 at 06:10
@АлексейНеудачин are you suggesting that's an error? It returns the size of the current object which i believe is the intended behaviour — Alan Birtles, Aug 07 '21 at 09:10
object you're talking about is not POD and even with POD you need `#pragma pack(1)` to do things like this — Алексей Неудачин, Aug 07 '21 at 09:52
@AlanBirtles thank you so mush, you are right, this it was the issue. — Loay Tarek, Aug 07 '21 at 11:10
@АлексейНеудачин thank you man, I appreciate your effort. — Loay Tarek, Aug 07 '21 at 11:14
@АлексейНеудачин you can have methods in a POD type: https://stackoverflow.com/questions/146452/what-are-pod-types-in-c. If the objects are being read and written by the same code you don't need to worry too much about padding — Alan Birtles, Aug 07 '21 at 12:37
@AlanBirtles so you're thinkin this guy has functions in class but doesn't have constructor? even `some_stuff() {}`? source class from where he'd copypasted this has one for sure. — Алексей Неудачин, Aug 07 '21 at 13:04

score 0 · Accepted Answer · answered Aug 07 '21 at 12:41

If opening iFile fails then the call to read will also fail and the body of the while loop will never execute. You should check the file opens successfully before using it:

ifstream iFile("shippingAddresses.dat", ios::binary);
if (!iFile)
{
    std::cout << "open failed\n";
    return;
}
while (iFile.read((char *)this, sizeof(*this)))
{
    display_adress();
}

Note that iFile.close(); is unnecessary as the destructor closes the file automatically

Why Can't Read The File(doesn't display the data)?

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