How Read from a Data File into a Structure of Vectors - c++

Question

I am trying to figure out how to store binary data that is saved to a .dat file "customer.dat" into a structure of vectors. I thought I have had it a few times, but with no luck.
Basically, I have a working method of storing the data into the .dat file, the newEntry function, but I can not seem to work out on how to bring the data back one set at a time into an order structure of vectors. The function in question is the searchDisplay function. Here is the code:
#include <iostream>
#include <fstream>
#include <vector>
#include <iomanip>
#include <string>
#include <cstring>
#include <cctype>
using namespace std;
const int NAME_SIZE = 51, ADDR_SIZE = 51, PHONE_SIZE = 14;
struct Client {
char name[NAME_SIZE];
char address1[ADDR_SIZE];
char address2[ADDR_SIZE];
char phone[PHONE_SIZE];
double acctBal;
double lastPay;
};
//void welcome();
int menu();
int newEntry();
int searchDisplay();
int main() {
int selection;
int option = 0;
int end;
//welcome();
while (option != 6) {
selection = menu();
if (selection == 1) {
cin.ignore();
end = newEntry();
if (end == 0) {
return 0;
}
} else if (selection == 2) {
end = searchDisplay();
if (end == 0) {
return 0;
}
}
}
return 0;
}
int menu() {
int selection;
cout << "User please enter the number that corresponds with what you wish to do..."
<< endl;
cout << "1) Add An Entry" << endl
<< "2) Search for a Specfic Person and erase." << endl;
cin >> selection;
return selection;
}
int newEntry() {
string input;
Client person;
char response = 'y';
//create file object and open file
fstream customer("customer.dat", ios::app | ios::binary);
if (!customer) {
cout << "Error opening file. Program aborting." << endl;
return 0;
}
do {
cout << "Enter person information:" << endl << endl;
cout << "Name: " << endl;
getline(cin, input);
strcpy(person.name, input.c_str());
cout << endl << person.name;
cout << endl << "Street Adress (And Apartment Number):" << endl;
cin >> person.address1;
getline(cin, input);
strcpy(person.address1, input.c_str());
cout << endl << "City, State, Zipcode: " << endl;
cin >> person.address2;
getline(cin, input);
strcpy(person.address2, input.c_str());
cout << endl << "Phone: " << endl;
cin >> person.phone;
getline(cin, input);
strcpy(person.phone, input.c_str());
cout << endl << "Account Balance: " << endl;
cin >> person.acctBal;
//input validation to ensure a non neg number
cin.ignore();
cout << endl << "Last Payment: " << endl;
cin >> person.lastPay;
//input validation to ensure a non neg number
customer.write(reinterpret_cast<char *>(&person), sizeof(person));
cout << endl << "Do you want to enter another record? (Enter Y for Yes, N for No) " << endl;
cin >> response;
cout << "_______________________________________________" << endl << endl;
if (toupper(response) == 'Y') {
cin.ignore();
}
} while (toupper(response) == 'Y');
customer.close();
return 1;
}
/********************************************
My main problem is with the below function
********************************************/
int searchDisplay() {
vector<Client> store(2);
Client foo;
int i = 0;
fstream customer("customer.dat", ios::in | ios::binary);
if (!customer) {
cout << "Error opening file. Program aborting." << endl;
return 0;
}
//MY HOPE WAS THIS WOULD STORE EACH SET OF DATA INTO THE STRUCTURE OF VECTORS
customer.read(reinterpret_cast<char *>(&store), sizeof (store[0]));
while (!customer.eof()){
cout << store[i].name << ":" << endl
<< store[i].address1 << endl
<< store[i].address2 << endl
<< store[i].phone << endl
<< store[i].acctBal << endl
<< store[i].lastPay << endl << endl;
i++;
customer.read(reinterpret_cast<char *>(&store), sizeof (store[i]));
}
customer.close();
return 1;
}
Sorry if any of the coding is a little off in its indenting, I was having issues with the method of putting the code onto the text block.
But yes, any help would be great. This is my first time working with vectors significantly and first time ever with more file classes.

Answer 1

Your first problem is the opening of the data file for writing. You are currently opening it with the flag "ios::app", when it should be "ios::out". Over here (gcc version 4.7.2) i get no output to file when opening the file with "ios::app".
Using "ios::out" it creates a file and dumps the data into it.
The second problem is in the line where you open and read the file. You are missing a "[0]". Check the corrected version below:
customer.read(reinterpret_cast<char *>(&store[0]), sizeof (store[0]));
Making this modifications you can get closer to the desired results.
The main problem here is that writing and reading binary files is a bit different from regular text files, that have indications of line endings, for example. You need to organize your data differently, which can be quite complicated. Try Serializing with Boost.