string read from file won't display in loop - c++

Question

The purpose of the following code is to take user input of 6 movie titles and realease dates, write that data to a file using fstream, then read the data into 2 string characters (line1 and line2) in a loop, such that the first loop will assign line1 and line2 the first movie title and year, and the second loop will assign line1 and 2 the 2nd movie title and year, and so on, until eof.
// array of structures
#include <iostream>
#include <string>
#include <sstream>
#include <istream>
#include <stdio.h>
#include <cctype>
#include <fstream>
#include <cassert>
#include <assert.h>
using namespace std;
#define NUM_MOVIES 6
struct movies_iit
{
string title;
int year;
}
films[NUM_MOVIES];
// global variables
char title[20], y, n;
int year;
string search;
// function 1
void sort_on_title(movies_iit films[], int n)
{
// Local struct variable used to swap records
movies_iit temp;
for (int i = 0; i < n - 1; i++)
{
for (int i = 0; i < n - 1; i++)
{
/* If s[i].title is later in alphabet than
s[i+1].title, swap the two records */
if (films[i].title > films[i + 1].title)
{
temp = films[i];
films[i] = films[i + 1];
films[i + 1] = temp;
}
}
}
}
//end function 1
//function query1 prototype
void query1(movies_iit movie);
// function query2 prototype
void query2(movies_iit movie);
// function 2 prototype
void printmovie(movies_iit movie);
int main()
{
// login
// username: user
// password: word
string mystr, pass, name, line1, line2;
int n;
char response;
// output object
ofstream fout("data.dat");
// input object
ifstream fin("data.dat");
assert(fin.is_open());
cout << "enter your username " << endl;
cin >> name;
cout << "enter your password " << endl;
cin >> pass;
cout << "\n" << endl;
if (name == "user" && pass == "word")
cout << "Welcome, user." << endl;
else
{
cout << "###" << "unrecognized username/password combination" << "\t" << "please try again" << "###" << endl;
system("PAUSE");
return 0;
}
cin.ignore(std::numeric_limits < std::streamsize > ::max(), '\n');
cout << "\n" << endl;
for (n = 0; n < NUM_MOVIES; n++)
{
cout << "Enter title: ";
getline(cin, films[n].title);
cout << "Enter year: ";
getline(cin, mystr);
stringstream(mystr) >> films[n].year;
}
cout << "\n" << endl;
for (int i = 0; i < NUM_MOVIES; ++i)
{
fout << films[i].title << "\n";
fout << films[i].year << "\n";
}
// sort records, function 1 call
sort_on_title(films, NUM_MOVIES);
cout << "\nYou have entered these movies:\n";
for (n = 0; n < NUM_MOVIES; n++)
printmovie(films[n]); // function 2 call
cout << "Perform an alphabetical search? (y/n)" << endl;
cin >> response;
if (response == 'y')
{
cout << "Please enter title" << endl;
cin >> title;
if (fin)
{
getline(fin, line1); // read first 2 recs
getline(fin, line2);
while (fin) // keep reading till the eof
{
if (line1 == "title")
{
cout << " >> " << line1 << endl;
cout << line2 << endl;
}
else
{
cout << line1 << endl;
cout << line2 << endl;
}
}
}
fin.close(); //close input file
response == n;
}
else if (response == 'n')
cout << "\n" << endl;
else
cout << "invalid entry" << endl;
cout << "\n" << endl;
}
// function 2 definition
void printmovie(movies_iit movie)
{
cout << movie.title;
cout << " (" << movie.year << ")\n";
}
// function query1 defintion
void query1(movies_iit movie)
{
if (movie.title == "title")
{
cout << " >> " << movie.title;
cout << " (" << movie.year << ")\n";
}
else
{
cout << movie.title;
cout << " (" << movie.year << ")\n";
}
}
// function query2 definition
void query2(movies_iit movie)
{
if (movie.year >= year)
{
cout << movie.title;
cout << " (" << movie.year << ")\n";
}
}
In the loop where I read values from the file into my strings, in my output it does not display the data stored in the strings. Why is that, and how can I fix the issue?
I realized that the code I originally posted didn't work; here is a functional one.

Answer 1

You need to close the 'fout' filestream before you try to read from it using 'fin'.
fout.close(); // <== Close the output file to flush the buffered I/O
The data you are writing to the file is likely buffered (not written to the file immediately). Your data.dat file is empty when you try to read it during your search.

Answer 2

Close the file in which data is being stored.
You are matching for string "title" and not input which user has provided.
getline() should be inside while loop ( as you want to match all the lines and not just 1st 2 records)
int main (){
//login
//username: user
//password: word
string mystr, pass, name, line1, line2;
int n;
char response;
//output object
ofstream fout ("data.dat");
//input object
cout << "enter your username "<<endl;
cin >> name;
cout << "enter your password "<<endl;
cin >> pass;
cout << "\n" << endl;
if (name == "user" && pass == "word")
cout << "Welcome, user." << endl;
else
{cout << "###" << "unrecognized username/password combination" << "\t" << "please try again" << "###" << endl;
//system("PAUSE");
return 0;
}
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
cout << "\n" << endl;
for (n=0; n<NUM_MOVIES; n++)
{
cout << "Enter title: ";
getline (cin,films[n].title);
cout << "Enter year: ";
getline (cin,mystr);
stringstream(mystr) >> films[n].year;
}
cout << "\n" << endl;
//###################################################################################################################
//write to file
//###################################################################################################################
for (int i = 0; i < NUM_MOVIES; ++i)
{
fout << films[i].title << "\n";
fout << films[i].year << "\n";
}
fout.close();
//sort records, function 1 call
sort_on_title(films, NUM_MOVIES);
cout << "\nYou have entered these movies:\n";
for (n=0; n<NUM_MOVIES; n++)
printmovie (films[n]); //function 2 call
ifstream fin("data.dat");
assert(fin.is_open());
//###################################################################################################################
//query 1
//###################################################################################################################
cout << "Perform an alphabetical search? (y/n)" << endl;
cin >> response;
if (response == 'y')
{cout << "Please enter title" << endl;
cin >> title;
if (fin.good())
{
while(!fin.eof()) //keep reading till the eof
{
getline(fin,line1); // read first 2 recs
if(!fin.eof())
getline(fin,line2);
if (line1 == title)
{
cout << " >> " << line1 << endl;
cout << line2 << endl;
}
// else
// {
// cout << line1 << endl;
// cout << line2 << endl;
// }
}
}
fin.close(); //close input file
response == n;
}
else if (response == 'n')
cout << "\n" << endl;
else
cout << "invalid entry" << endl;
cout << "\n" << endl;
}