C++ reading database from the file into the array

Discussion in 'C++' started by ianenis.tiryaki@gmail.com, Mar 10, 2007.

  1. Guest

    well i got this assignment which i dont even have a clue what i am
    supposed to do. it is about reading me data from the file and load
    them into a parallel array here is the question:

    Step (1)

    Your first task is to write a program which reads this file into two
    parallel arrays in memory. One array contains the titles, and the
    other array contains the authors. The arrays are 'parallel' in the
    sense that the n-th element of the authors array contains the authors
    associated with the n-th element of the titles array. Although the
    data in the test file describes only a few books you should dimension
    your arrays for an arbitrary number of books in the live data file
    (which may be different from the test file). The size of the arrays
    should be defined in your program by the declaration const int
    ARRAY_SIZE = 1000.

    For the purpose of this assignment (so as not to make it too
    complicated) you should declare your two arrays at file scope (i.e.
    outside any function and before the function main()). The declarations
    should be as follows:

    string bookTitle [ARRAY_SIZE];

    string bookAuthor [ARRAY_SIZE];

    Write a function whose signature is as follows:

    int loadData (string pathname)

    The function loadData should open the data file located in the path on
    your hard disk specified by pathname. If it cannot open the file for
    some reason, it should return a value of -1 as an error result.
    Otherwise it should read the data in the file into the two parallel
    arrays, and return the number of book records that it read.

    Now write a function whose signature is as follows:

    void showAll (int count)

    The parameter count provides the number of books actually stored in
    the database (i.e the value returned by the function loadData()).
    showAll() should read the designated number of records in the parallel
    arrays and display it on the screen in the order it appears in the
    database, in single column format as follows (using the data in the
    example file):

    Objects First with Java (Barnes and Kolling)

    Game Development Essentials (Novak)

    The Game Maker's Apprentice (Overmars)

    C++ Programming: From Problem Analysis... (Malik)

    ....

    ....

    Audio for Games (Brandon)

    Now test your work so far, by writing a main() function to prompt the
    user for the path to the data file, open and read the file to the
    parallel arrays using the function loadData() (providing error
    messages and recovery as appropriate if the file doesn't exist). Then
    display the contents of the file using showAll().

    Step (2)

    Extend your program into a menu driven application to query the
    database. When the program starts it should ask the user for the path
    to the data file, and read the data into the parallel arrays, as in
    step 1.

    Then it should enter a loop, in each iteration of which it prompts the
    user for what they want to do. The actions are as follows depending on
    how the user responds to the prompt. See the sample dialog below to
    see how this works in practice.

    Q or q: Quit. The program terminates.

    A or a: Search by Author. The program displays all records which
    contain the designated text somewhere in the author field. You should
    use a function with the following signature for this purpose: int
    showBooksByAuthor (int count, string name). This function should
    display all books whose author field contains the string passed in the
    parameter called name. It returns the number of books displayed. count
    specifies the number of books in the database.

    T or t: Search by Title. The program displays all records which
    contain the designated text somewhere in the title field. You should
    use a function with the following signature for this purpose: int
    showBooksByTitle (int count, string title). This function should
    display all books whose title field contains the string passed in the
    parameter called title. It returns the number of books displayed.
    count specifies the number of books in the database.

    Sample Dialog

    Note: In the example below, the user's input is in BOLD. The program
    output is not.

    Welcome to Colin's Library Database.

    Please enter the name of the backup file: C:\library.txt

    14 records loaded successfully.

    Enter Q to Quit, A to search by Author, T to search by Title: A

    Author's Name: Malik

    C++ Programming: From Problem Analysis... (Malik)

    C++ Programming: Program Design Including... (D. S. Malik)

    2 records found.

    Enter Q to Quit, A to search by Author, T to search by Title: A

    Author's Name: Goble

    0 records found.

    Enter Q to Quit, A to search by Author, T to search by Title: T

    Title: Game

    Game Development Essentials (Novak)

    The Game Maker's Apprentice (Overmars)

    Game Character Development with Maya (Ward)

    Developing Games in Java (Brackeen)

    Audio for Games (Brandon)

    5 records found.

    Enter Q to Quit, A to search by Author, T to search by Title: Q
     
    , Mar 10, 2007
    #1
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  2. wrote:
    > well i got this assignment which i dont even have a clue what i am
    > supposed to do. it is about reading me data from the file and load
    > them into a parallel array here is the question:
    >


    If you really don't have any clue I'm not sure how you think you are
    going to get one by posting your assignment here. Have you not been
    attending lessons? Did you get stuck at the beginning and never catch
    up? Did you never ever really get it? Some people just aren't mentally
    suited to programming, this might be when you find out.

    More optimistically - first program is always difficult. The only answer
    is to attempt to write some code. You're fortunate that you have some
    detailed instructions. Follow them as best you can. When you have
    written some code and you have *specific* questions, post the code with
    the question and you'll get lots of help.

    Failing that I believe there are sites on the internet where you can pay
    to get your homework done. If you think that is a good idea then you
    really are beyond hope.

    john
     
    John Harrison, Mar 10, 2007
    #2
    1. Advertising

  3. Guest

    i started with this code and i am trying to read file into the array
    but i am not sure if it is right. By the way i want to learn how to do
    it instead of getting it done so if you can help me i would really
    appreciae it!

    thanks!

    #include <iostream>
    #include <iomanip>
    #include <string>
    #include <cmath>
    #include<stdio.h>

    using namespace std;

    main()
    {
    // to read a database from the file:

    FILE *fp;
    fp=fopen("test.txt","rb");

    //parallel array:

    const int MAX= 100;
    string name[MAX]; //name of author array
    string book[MAX]; // name of the books array
    int i;



    //to reset the array elements to zero:

    for (int i=0; i < MAX; i++)
    {
    name=0;
    book=0;
    }
     
    , Mar 10, 2007
    #3
  4. red floyd Guest

    wrote:
    > i started with this code and i am trying to read file into the array
    > but i am not sure if it is right. By the way i want to learn how to do
    > it instead of getting it done so if you can help me i would really
    > appreciae it!
    >
    > thanks!
    >
    > #include <iostream>
    > #include <iomanip>
    > #include <string>
    > #include <cmath>
    > #include<stdio.h>

    unneeded. Use iosreams instead
    >
    > using namespace std;
    >
    > main()

    implicit int is not supported in C++ use int main()

    > {
    > // to read a database from the file:
    >
    > FILE *fp;
    > fp=fopen("test.txt","rb");

    // use an IOStream rather than an FP
    >
    > //parallel array:
    >
    > const int MAX= 100;
    > string name[MAX]; //name of author array
    > string book[MAX]; // name of the books array

    use a struct, rather than separate arrays. The struct should contain
    two elements (you should be able to figure out what they are).
    use a vector of said struct, rather than a fixed size. What happens if
    there's more than 100 entries in the file?

    > int i;
    >
    >
    >
    > //to reset the array elements to zero:
    >
    > for (int i=0; i < MAX; i++)
    > {
    > name=0;
    > book=0;

    unneeded, they strings in the array are default initialized.
    > }
    >


    And?
     
    red floyd, Mar 11, 2007
    #4
  5. red floyd Guest

    Let me expound a little bit on one of my comments.

    I told you to use iostreams and forget stdio and FILE*.

    You have correctly chosen to use std::string for your strings, instead
    of a char array. This is a *GOOD THING*. However, stdio doesn't know
    how to properly handle std::strings. Iostreams, on the other hand, do
    know how to deal with std::string.

    Therefore you should forget about C-style I/O (stdio) and use C++ style
    I/O (IOStreams).
     
    red floyd, Mar 11, 2007
    #5
  6. wrote:
    > i started with this code and i am trying to read file into the array
    > but i am not sure if it is right. By the way i want to learn how to do
    > it instead of getting it done so if you can help me i would really
    > appreciae it!
    >
    > thanks!
    >
    > #include <iostream>
    > #include <iomanip>
    > #include <string>
    > #include <cmath>
    > #include<stdio.h>
    >
    > using namespace std;
    >
    > main()
    > {
    > // to read a database from the file:
    >
    > FILE *fp;
    > fp=fopen("test.txt","rb");
    >
    > //parallel array:
    >
    > const int MAX= 100;
    > string name[MAX]; //name of author array
    > string book[MAX]; // name of the books array


    Straight away you have done something that your assignment said you
    should not do.

    Go back to you assignment, re-read that part where it says 'declare your
    two arrays at file scope' and 'The declarations should be as follows'.

    Then read the part that says 'Now write a function', start with that
    part don't start with main, leave main until you get to the part that
    says 'Now test your work so far'.

    Your professor has obviously made an effort to make this assignment as
    easy as possible, you should at least follow his instructions.

    john
     
    John Harrison, Mar 11, 2007
    #6
  7. >
    > use a struct, rather than separate arrays. The struct should contain
    > two elements (you should be able to figure out what they are).
    > use a vector of said struct, rather than a fixed size. What happens if
    > there's more than 100 entries in the file?
    >
    >


    His assignment specifically says use parallel fixed size arrays.

    john
     
    John Harrison, Mar 11, 2007
    #7
  8. Tim Slattery Guest

    red floyd <> wrote:


    >> const int MAX= 100;
    >> string name[MAX]; //name of author array
    >> string book[MAX]; // name of the books array

    >use a struct, rather than separate arrays.


    I'd agree with that, except that the assignment specifically said to
    use parallel arrays.

    --
    Tim Slattery

    http://members.cox.net/slatteryt
     
    Tim Slattery, Mar 12, 2007
    #8
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