Thread: Interactive Files and Streams Program Failure

Brand new to the board - I am taking an intro course and have been sailing through the programs until this one. It is a distance learning class with an ?instructor? There are 45 programs to write and I am stuck on the 37th one. Here goes:

There is a text file I had to create that has information on computer terminals in a network. There are 100 terminals and the info on the nth terminal is on the nth line of the file. The computer info is terminal type (string), building located in (string), transmission rate (integer), access code (character), and date of last service (month, day, year).

Write a program to read terminal numbers from the keyboard and directly access the line in the file for each terminal by moving the read position directly to that line. The program should retrieve and display the terminal info.

This is Chapter 9 and covers ifstream and ofstream objects as well as additional stream features. So, it is not advanced - did I mention it was an intro course?

I have reworked the code so much...I was getting the terminal info, but now it just hangs before getting to that point (have to control-C to get out). I know it is something simple and I am over thinking the problem. But I can't figure out what it is. A little detailed in my problem explanation I know but what can I say – programming! Any and all help is appreciated.
Thanks!

Code:

#include <iostream>
#include <string>
#include <iomanip>    // not used yet
#include <fstream>
#include <cassert> 
using namespace std;

int main()
{
    ifstream readInFile("terminalInfo.txt");
    // ensures the input file is open
    assert(readInFile.is_open());
    // set line length for finding data
    const int LINE_LENGTH = 100;
    // variable declarations
    string terminalType,
           terminalBuilding,
           date;
    char accessCode,
         response;
    int lineNumber,
        transmissionRate,
        terminalNumber;
    do
    {
        cout << "\nEnter terminal number: ";
        cin >> terminalNumber;
        // 
        if (terminalNumber > 0 && terminalNumber <= 100)
        {
            // find the beginning of the line for that terminal number
            readInFile.seekg(terminalNumber * LINE_LENGTH, ios::beg);
            // read in terminal information from file
            readInFile >> terminalType >> terminalBuilding >> transmissionRate
                 >> accessCode >> date;
            // print terminal information to screen
            cout << "\nInformation for computer number: " << terminalNumber
                    << "\nType of terminal: " << terminalType 
                    << "\nis located in the " << terminalBuilding << " building"
                    << "\nhas a transmission rate of: " << transmissionRate 
                    << "\nan access code of: " << accessCode 
                    << "\nand the last service date was on: " << date;
        }
        cerr << "\nTerminal number is invalid."
               << "\nValid numbers are from 1 through 100."
               << "\nTry Again? (Y or N): ";
        cin >> response;
    }
    while (response != 'N' && response != 'n');
    return 0;
}

Code:

>            cin >> terminalType >> terminalBuilding >> transmissionRate
                 >> accessCode >> date;

This reads from the console (cin stands for Console Input). You want to read from the file that was previously opened:

Code:

            readInFile >> terminalType >> terminalBuilding >> transmissionRate
                 >> accessCode >> date;

Thanks!
I changed the code above, that solves the hang problem until I added an else to the if. It was rolling right through to the cerr statements. Adding the else, solved that, but now it hangs again.

I also need to work on the garbage (or nothing) I am getting, instead of the terminal info, from the file.
I think that I need to define the size of each of the fields in the readinFile, the LINE_LENGTH is an arbitrary number I chose. That may have something to do with the garbage issue. I am going back to the text to see what I can find.

I may just have to start all over.

I don't understand why this program is giving me such fits.

Thanks again.

think that I need to define the size of each of the fields in the readinFile, the LINE_LENGTH is an arbitrary number I chose.

If you're using a windows machine, each line will probably need to be exactly 98 characters (the <CR> and <LF> would add two to equal 100), so you'd pad the end of the line with spaces. Also each piece of data within the line should be separated by at least one space.

When using seekg() to access a record, naturally each record must be a fixed number of characters long, or seekg() won't find the right record.